Aqueous dispersions

ABSTRACT

Aqueous dispersions of cationic water-soluble polymers are provided, as well as processes for making and methods of using the same.

[0001] This application is a continuation of U.S. application Ser. No.09/200,322, filed Nov. 25, 1998, which is a continuation-in-part of U.S.application Ser. No. 08/725,325, filed Oct. 3, 1996, both of which arehereby incorporated by reference in their entireties.

BACKGROUND OF THE INVENTION

[0002] This invention relates to aqueous dispersions comprised ofwater-soluble polymers, processes for making said dispersions, andmethods of using said dispersions in water treating, dewatering, waterclarification, papermaking, oil field, soil conditioning, foodprocessing, mineral processing, and biotechnological applications.

[0003] U.S. Pat. No. 4,380,600 discloses a process for producing anaqueous dispersion of water-soluble polymers. The aqueous dispersion maycontain inorganic salt. However, the aqueous dispersions exemplifiedtherein have disadvantageously high bulk viscosities.

[0004] U.S. Pat. No. 4,673,704 and EP 0 170 394 A2 disclose productscomprised of particles above 20 microns in size of a high molecularweight polymer gel interconnected by a continuous phase that is anaqueous solution of an equilibrating agent that holds the water contentof the particles in equilibrium with the water content of the aqueousphase and that prevents substantial agglomeration of the particles inthe fluid product. Although these references are entitled “AqueousPolymer Dispersions,” the products disclosed therein are distinguishedfrom the aqueous dispersions of U.S. Pat. No. 4,380,600 and from theaqueous dispersions of the instant invention in that the particles ofU.S. Pat. No. 4,673,704 and EP 0 170 394 A2 are not generally heldsuspended in a continuous matrix of the aqueous phase but insteadgenerally rest substantially in contact with one another but slide overone another. A process for dispersing the polymer gel into an aqueoussolution of an equilibrating agent and working the polymer while in thatmedium is disclosed in U.S. Pat. No. 4,778,836 and EP 0 169 674 B1.Also, U.S. Pat. No. 4,522,968 discloses a process for dispersing certainpowdered water-soluble homopolymers or copolymers in an aqueous solutioncontaining a polymer of ethylene oxide and/or propylene oxide.

[0005] U.S. Pat. Nos. 4,929,655 and 5,006,590 disclose processes forpreparing aqueous dispersions of water-soluble polymers by polymerizingbenzyl-containing monomers in the presence of an organic high molecularmultivalent cation and a multivalent anionic salt. The benzylgroup-containing monomer may be replaced by a hydrophobic alkylgroup-containing monomer as in EP 0 525 751. Numerous references concernthese and similar polymers, e.g. U.S. Pat. Nos. 5,332,506; 5,332,507;5,330,650; 5,292,793, 5,435,922; 5,466,338; EP 0 595 156 A1; EP 0630 909A1; EP 0657478 A2; EP 0629 583 A2; EP 0 617 991 A1, EP 0 183 466 B1, EP0 637 598 A2; EP 0 717 056 A2; JP 61-6396; JP 61-6397; JP 61-6398; JP62-262799; JP 64-15130; JP 2-38131; JP 62 15251; JP 61-138607; Hei6-329866; and JP 62-100548. Although some of the aqueous dispersions inthese references have relatively low bulk viscosities, the need toinclude special monomers containing aromatic or hydrophobic alkyl groupsin order to render the polymer insoluble in salt solution may bedisadvantageous because the special monomers may be expensive anddilutive of the polymer effect in a specific application.

[0006] The effect of salts on the solubility of various substances inaqueous solution is well discussed in the scientific literature. The“Hofineister” series ranks anions according to their ability to increaseor decrease the solubility of substances in water. Although positions inthe ranking may vary slightly, depending on the substance, a generallyaccepted ranking of the anions is:

[0007]

[0008] Kosmotropic salts generally decrease the solubility of substancesin water. For instance, the Hofineister ranking apparently guided thechoice of salts for precipitating cationic water soluble polymers,containing hydrophobic groups, in U.S. Pat. Nos. 4,929,655 and5,006,590, as well as EP 0 630 909 A1, EP 0 525 751 A1, and EP 0 657 478A2, as evidenced by their use of strongly kosmotropic salts containingsulfate and phosphate anions. On the other hand, chaotropic saltsgenerally increase the solubility of substances in water.

[0009] There are numerous means known to those skilled in the art fordetermining whether a particular salt is kosmotropic or chaotropic.Representative salts which contain anions such as sulfate, fluoride,phosphate, acetate, citrate, tartrate and hydrogenphosphate arekosmotropic. Representative salts which contain anions such asthiocyanate, perchlorate, chlorate, bromate, iodide, nitrate and bromideare chaotropie. The chloride anion is generally considered to be atabout the middle of the Hofineister ranking, being either weaklychaotropic or weakly kosmotropic, depending on the particular system. Inthe instant invention, although occasionally chaotropic, inorganic saltswhich contain the chloride anion tend to be kosmotropic.

[0010] Small amounts of sodium thiocyanate, for instance about 0.1% byweight, on total, have been reported to be useful as stabilizers forpolymer dispersions as in EP 0 657 478 A2, where (NH₄)₂SO₄ was used todeposit the polymer. Sodium thiocyanate and sodium iodide have beenreported to be useful as stabilizers for hydroxylamine-containingwater-soluble polymer systems, as in EP 0 514 649 A1. U.S. Pat. No.3,234,163 teaches that small amounts of thiocyanate salts, preferably0.1 to 1 percent, based on the weight of the polymer, are useful forstabilizing polyacrylamide solutions.

[0011] The Hofineister ranking has been observed in solutions of highmolecular weight, water-soluble polymers. For instance, the effect ofvarious salts on the solubility of synthetic, water-soluble polymers wasexplored by Shuji Saito, J. Polym. Sci.: Pt. A, Vol. 7, pp. 1789-1802(1969). This author discussed the effect of various anions on polymersolubility and stated “This anionic order seems to be independent of thetype of counter cations and is in line with Hofineister's lyotropicseries for anions.” Similarly, in M. Leca, Polymer Bulletin, Vol. 16,pp. 537-543, 1986, the viscosity of polyacrylamide, as determined in 1Nsolutions of various salts, was found to increase in the order HPO₄²⁻<H₂O<Br⁻<NO₃ ⁻<I⁻=BrO₃ ⁻<ClO₃ ⁻=SCN⁻. The viscosities were reported tobe higher in more chaotropic salt solutions than in less chaotropic, orkosmotropic, salt solutions. Certain novel cationic polyelectrolytes,termed ionene polymers, were reported (D. Casson and A. Rembaum,Macromolecules, Vol. 5, No. 1, 1972, pp. 75-81) to be insoluble ineither 0.4 M potassium iodide or 0.4 M potassium thiocyanate. It hasalso been reported (W-F. Lee and C-C. Tsai, J. Appl. Polym. Sci., Vol.52, pp. 1447-1458, 1994) that poly(trimethyl acrylamido propyl ammoniumiodide) did not dissolve in 0.5 M Na₂ClO₄ or 0.5 M NaNO₃.

[0012] Certain anionic organic salts, such as hydrotropes andsurfactants, also tend to increase the solubility of substances inwater. However, poly(allylammonium chloride) was reported (T. Itaya etal., J. Polym. Sci., Pt. B: Polym. Phys., Vol. 32, pp. 171-177, 1994,and references 3, 5 and 6 therein; also Macromolecules, Vol 26, pp.6021-6026, 1993) to precipitate in solutions containing the sodium saltof p-ethylbenzenesulfonate, p-propylbenzenesulfonate ornaphthalenesulfonate. Poly(4-vinyl pyridine) quatemized with butylchloride and poly(allylammonium chloride) were reported (M. Satoh, E.Yoda, and J. Komiyama, Macromolecules, Vol. 24, pp. 1123-27, 1991) toprecipitate in solutions of Nal and also in solutions containing thesodium salt of p-ethylbenzenesulfonate, respectively. Compositionscomprising sulphonated hydrocarbon surfactants and hydrophilic cationicpolymers were disclosed in U.S. Pat. No. 5,130,358. Mixtures ofchaotropic salts, or anionic organic salts, and kosmotropic salts may beused to precipitate cationic polymers as in U.S. application Ser. No.08/725,436, filed even date herewith.

[0013] Aqueous dispersions of water-soluble polymers are disclosed inU.S. Pat. Nos. 5,403,883; 5,480,934; 5,541,252; EP 0 624 617 A1; EP 0573 793 A1; and WO 95/11269. A problem remains in that the aqueousdispersions exemplified in these references still have relatively highbulk viscosities.

[0014] A process for preparing crosslinked copolymer beads fromwater-soluble monomers in an aqueous solution containing an inorganicsalt and a dispersant is disclosed in U.S. Pat. No. 5,498,678 and EP 0604 109 A2. Mixtures of aqueous dispersions and water-in-oil emulsionsare disclosed in Hei 7-62254 and Hei 6-25540. The addition of a nonionicsurfactant and an oleaginous liquid to an aqueous dispersion to maintainflowability is disclosed in U.S. Pat. No. 5,045,587. Mixtures ofcationic polymers are disclosed in Sho-52-71392 and homogeneous blendsof water-soluble polymers are disclosed in U.S. Pat. No. 4,835,206 andEP 0 262 945 B1. Bimodal cationics for water clarification are disclosedin U.S. Pat. Nos. 4,588,508 and 4,699,951. Blends of water-in-oilpolymer emulsions are disclosed in U.S. patent application Ser. No.08/408,743.

[0015] In spite of the effort to make satisfactory aqueous dispersions,the problem remains of producing aqueous dispersions of high molecularweight water soluble polymers that have advantageously low bulkviscosities, high active solids content, minimal quantities of dilutivematerial, and that dissolve readily and can be prepared with a broadrange of cationicity.

SUMMARY OF THE INVENTION

[0016] This problem is solved in the present invention by providingnovel aqueous dispersions of high molecular weight water-soluble orwater-swellable polymers, as well as processes for making and methods ofusing said aqueous dispersions. Accordingly, an aqueous dispersion ofpolymers is provided which comprises: (a) a first cationic water-solubleor water-swellable polymer; and (b) at least one second water-solublepolymer different from said first polymer; and (c) a kosmotropic salt;and (d) a chaotropic salt, wherein the amounts of said (b), (c) and (d)are such that a homogeneous composition is obtained in the absence ofsaid (b). In another embodiment, an aqueous dispersion of polymers isprovided which comprises: (a) a first cationic water-soluble orwater-swellable polymer; and (b) at least one second water-solublepolymer different from said first polymer; and (c) a kosmotropic salt;and (d) an anionic organic salt, wherein the amounts of said (b), (c)and (d) are such that a homogeneous composition is obtained in theabsence of said (b).

[0017] In another embodiment, an aqueous dispersion of polymers isprovided which is comprised of (a) a discontinuous phase containingpolymer that is comprised predominately of a first cationicwater-soluble or water-swellable polymer having at least one firstrecurring unit of the formula (I),

[0018] wherein R₁ is H or CH₃, A is O or NH, B is an alkylene orbranched alkylene or oxyalkylene group having from 1 to 5 carbons, R₂ isa methyl, ethyl, or propyl group, R₃ is a methyl, ethyl, or propylgroup, R₄ is a methyl, ethyl or propyl group, and X is a counterion; and(b) at least one second water-soluble polymer different from said firstpolymer; wherein, if said first polymer is further comprised of a secondrecurring unit of formula (I) wherein R₁ is H or CH₃, A is O or NH, B isan alkylene or branched alkylene or oxyalkylene group having from 1 to 5carbons, X is a counterion, and R₂, R₃ or R₄ is selected from the groupconsisting of C₄-C₁₀ alkyl, benzyl, and C₂H₄C₆H₅, then the amount ofsaid first recurring unit is greater than the amount of said secondrecurring unit on a molar basis, and wherein, if said R₂, R₃ and R₄ insaid first recurring unit together contain a total of 3 carbon atoms,then said first polymer is devoid of hydrophobic recurring units.

[0019] In another embodiment, an aqueous dispersion of polymers isprovided which comprises: (a) a first cationic water-soluble orwater-swellable polymer having at least one recurring unit of theformula (I), wherein R₁ is H or CH₃, A is O or NH, B is an alkylene orbranched alkylene or oxyalkylene group having from 1 to 5 carbons, R₂ isa methyl, ethyl, or propyl group, R₃ is a methyl, ethyl, or propylgroup, R₄ is an alkyl or substituted alkyl group having from 1 to 10carbons, or an aryl or substituted aryl group having from 6 to 10carbons, X is a counterion, and R₂, R₃, and R₄ together contain a totalof at least 4 carbon atoms; and (b) at least one second water-solublepolymer different from said first polymer, wherein a homogeneouscomposition is obtained in the absence of said (b).

[0020] In another embodiment, a process for making an aqueous dispersionof polymers is provided which comprises polymerizing vinyl-additionmonomers to form an aqueous dispersion comprised of a first cationicwater-soluble or water-swellable polymer, wherein said polymerizing iscarried out in the presence of an aqueous composition comprised of (a)at least one second water-soluble polymer different from said firstpolymer; (b) a kosmotropic salt; and (c) a chaotropic salt, wherein theamounts of said (a), (b) and (c) are such that a homogeneous compositionis obtained if said polymerizing is carried out in the absence of said(a).

[0021] In another embodiment, a process for making an aqueous dispersionof polymers is provided which comprises polymerizing vinyl-additionmonomers to form an aqueous dispersion comprised of a first cationicwater-soluble or water-swellable polymer, wherein said polymerizing iscarried out in the presence of an aqueous composition comprised of (a)at least one second water-soluble polymer different from said firstpolymer; (b) a kosmotropic salt; and (c) of an anionic organic salt,wherein the amounts of said (a), (b) and (c) are such that a homogeneouscomposition is obtained if said polymerizing is carried out in theabsence of said (a).

[0022] In another embodiment, a process for making an aqueous dispersionof polymers is provided which comprises polymerizing vinyl-additionmonomers comprised of at least one monomer of the formula (II)

[0023] to form an aqueous dispersion comprised of a first cationicwater-soluble or water-swellable polymer, wherein R₁ is H or CH₃, A is Oor NH, B is an alkylene or branched alkylene or oxyalkylene group havingfrom 1 to 5 carbons, R₂ is a methyl, ethyl, or propyl group, R₃ is amethyl, ethyl, or propyl group, R₄ is a methyl, ethyl or propyl group,and X is a counterion; wherein said polymerizing is carried out in thepresence of an aqueous composition comprised of at least one secondwater-soluble polymer different from said first polymer; wherein, ifsaid vinyl-addition monomers are further comprised of a second monomerof formula (II) wherein R₁ is H or CH₃, A is O or NH, B is an alkyleneor branched alkylene or oxyalkylene group having from 1 to 5 carbons, Xis a counterion, and R₂, R₃ or R₄ is selected from the group consistingof C₄-C₁₀ alkyl, benzyl, and C₂H₄C₆H₅, then the amount of said firstmonomer is greater than the amount of said second monomer on a molarbasis, and wherein, if said R₂, R₃ and R₄ in said first monomer togethercontain a total of 3 carbon atoms, then said first polymer is devoid ofhydrophobic recurring units.

[0024] In another embodiment, a process for making an aqueous dispersionof polymers is provided which comprises polymerizing vinyl-additionmonomers comprised of at least one monomer of the formula (II) to forman aqueous dispersion comprised of a first water-soluble orwater-swellable cationic polymer, wherein R₁ is H or CH₃, A is O or NH,B is an alkylene or branched alkylene or oxyalkylene group having from 1to 5 carbons, R₂ is a methyl, ethyl, or propyl group, R₃ is a methyl,ethyl, or propyl group, R₄ is an alkyl or substituted alkyl group havingfrom 1 to 10 carbons, or an aryl or substituted aryl group having from 6to 10 carbons, X is a counterion, and R₂, R₃, and R₄ together contain atotal of at least 4 carbon atoms; and wherein said polymerizing iscarried out in the presence of an aqueous composition comprised of anamount of at least one second water-soluble polymer different from saidfirst polymer; and wherein said amount of said second polymer is suchthat a homogeneous composition is obtained if said polymerizing iscarried out in the absence of said second polymer.

[0025] In another embodiment, a process for blending two or more aqueousdispersions is provided, comprising intermixing (a) a first aqueousdispersion of a water-soluble or water-swellable polymer with (b) asecond aqueous dispersion of a water-soluble or water-swellable polymer,wherein said (a) is different from said (b), to form a third aqueousdispersion.

[0026] In another embodiment, a method of dewatering a suspension ofdispersed solids is provided which (a) intermixing an aqueous dispersionof polymers, or aqueous admixture thereof, in an amount effective fordewatering, with a suspension of dispersed solids, and (b) dewateringsaid suspension of dispersed solids, said aqueous dispersion beingcomprised of (i) a first cationic water-soluble or water-swellablepolymer; and (ii) at least one second water-soluble polymer differentfrom said first polymer; and (iii) a kosmotropic salt; and (iv) achaotropic salt, wherein the amounts of said (ii), (iii) and (iv) aresuch that a homogeneous composition is obtained in the absence of said(ii).

[0027] In another embodiment, a method of dewatering a suspension ofdispersed solids is provided which comprises (a) intermixing an aqueousdispersion of polymers, or aqueous admixture thereof, in an amounteffective for dewatering, with a suspension of dispersed solids, and (b)dewatering said suspension of dispersed solids, said aqueous dispersionbeing comprised of (i) a first cationic water-soluble or water-swellablepolymer; and (ii) at least one second water-soluble polymer differentfrom said first polymer; and (iii) a kosmotropic salt; and (iv) ananionic organic salt, wherein the amounts of said (ii), (iii) and (iv)are such that a homogeneous composition is obtained in the absence ofsaid (ii).

[0028] In another embodiment, a method of dewatering a suspension ofdispersed solids is provided which comprises (a) intermixing an aqueousdispersion of polymers, or aqueous admixture thereof, in an amounteffective for dewatering, with a suspension of dispersed solids, and (b)dewatering said suspension of dispersed solids, said aqueous dispersionbeing comprised of (i) a discontinuous phase containing polymer that iscomprised predominately of a first cationic water-soluble orwater-swellable polymer having at least one first recurring unit of theformula (I), wherein R₁ is H or CH₃, A is O or NH, B is an alkylene orbranched alkylene or oxyalkylene group having from 1 to 5 carbons, R₂ isa methyl, ethyl, or propyl group, R₃ is a methyl, ethyl, or propylgroup, R₄ is a methyl, ethyl or propyl group, and X is a counterion;(ii) at least one second water-soluble polymer different from said firstpolymer; wherein, if said first polymer is further comprised of a secondrecurring unit of formula (I) wherein R₁ is H or CH₃, A is O or NH, B isan alkylene or branched alkylene or oxyalkylene group having from 1 to 5carbons, X is a counterion, and R₂, R₃ or R₄ is selected from the groupconsisting of C₄-C₁₀ alkyl, benzyl, and C₂H₄C₆H₅, then the amount ofsaid first recurring unit is greater than the amount of said secondrecurring unit on a molar basis, and wherein, if said R₂, R₃ and R₄ insaid first recurring unit together contain a total of 3 carbon atoms,then said first polymer is devoid of hydrophobic recurring units.

[0029] In another embodiment, a method of dewatering a suspension ofdispersed solids is provided which comprises (a) intermixing an aqueousdispersion of polymers, or aqueous admixture thereof, in an amounteffective for dewatering, with a suspension of dispersed solids, and (b)dewatering said suspension of dispersed solids, said aqueous dispersionbeing comprised of (i) a first cationic water-soluble or water-swellablepolymer having at least one recurring unit of the formula (I), whereinR₁ is H or CH₃, A is O or NH, B is an alkylene or branched alkylene oroxyalkylene group having from 1 to 5 carbons, R₂ is a methyl, ethyl, orpropyl group, R₃ is a methyl, ethyl, or propyl group, R₄ is an alkyl orsubstituted alkyl group having from 1 to 10 carbons, or an aryl orsubstituted aryl group having from 6 to 10 carbons, X is a counterion,and R₂, R₃, and R₄ together contain a total of at least 4 carbon atoms;and (ii) at least one second water-soluble polymer different from saidfirst polymer, wherein a homogeneous composition is obtained in theabsence of said (ii).

[0030] In another embodiment, a process for producing substantially drywater-soluble or water-swellable vinyl-addition polymer particles isprovided which comprises (a) spray-drying a vinyl-additionpolymer-containing aqueous dispersion into a gas stream with a residencetime of about 8 to about 120 seconds and at an outlet temperature ofabout 70° C. to about 150° C. and (b) collecting resultant polymerparticles.

[0031] In another embodiment, substantially dry water-soluble orwater-swellable polymer particles are provided which are comprised of(a) a first cationic water-soluble or water-swellable polymer; and (b)at least one second water-soluble polymer different from said firstpolymer; and (c) a kosmotropic salt; and (d) a chaotropic salt, whereinabout 90% or more of said polymer particles each individually containsboth said (a) and said (b), said particles having a bulk density ofabout 0.4 grams per cubic centimeter to about 1.0 grams per cubiccentimeter.

[0032] In another embodiment, there is provided a method comprising (a)intermixing a composition comprising substantially dry water-soluble orwater-swellable polymer particles comprised of (i) a first cationicwater-soluble or water-swellable polymer; and (ii) at least one secondwater-soluble polymer different from said first polymer; and (iii) akosmotropic salt; and (iv) a chaotropic salt, wherein about 90% or moreof said polymer particles each individually contains both said (i) andsaid (ii), said particles having a bulk density of about 0.4 grams percubic centimeter to about 1.0 grams per cubic centimeter, with water toform an aqueous polymer admixture, (b) intermixing said aqueous polymeradmixture, in an amount effective for dewatering, with a suspension ofdispersed solids, and (c) dewatering said suspension of dispersedsolids.

[0033] In another embodiment, there is provided a method comprising (a)intermixing a composition comprising substantially dry water-soluble orwater-swellable polymer particles comprised of (i) a first cationicwater-soluble or water-swellable polymer; and (ii) at least one secondwater-soluble polymer different from said first polymer; and (iii) akosmotropic salt; and (iv) an anionic organic salt, wherein about 90% ormore of said polymer particles each individually contains both said (i)and said (ii), said particles having a bulk density of about 0.4 gramsper cubic centimeter to about 1.0 grams per cubic centimeter, with waterto form an aqueous polymer admixture, (b) intermixing said aqueouspolymer admixture, in an amount effective for dewatering, with asuspension of dispersed solids, and (c) dewatering said suspension ofdispersed solids.

[0034] In another embodiment, there is provided a method comprising (a)intermixing a composition comprising substantially dry water-soluble orwater-swellable polymer particles comprised of (i) a first cationicwater-soluble or water-swellable polymer having at least one recurringunit of the formula (1), wherein R₁ is H or CH₃, A is O or NH, B is analkylene or branched alkylene or oxyalkylene group having from 1 to 5carbons, R₂ is a methyl, ethyl, or propyl group, R₃ is a methyl, ethyl,or propyl group, R₄ is an alkyl or substituted alkyl group having from 1to 10 carbons, or an aryl or substituted aryl group having from 6 to 10carbons, X is a counterion, and R₂, R₃, and R₄ together contain a totalof at least 4 carbon atoms; and (ii) at least one second water-solublepolymer different from said first polymer, wherein about 90% or more ofsaid polymer particles each individually contains both said (i) and said(ii), said particles having a bulk density of about 0.4 grams per cubiccentimeter to about 1.0 grams per cubic centimeter, with water to forman aqueous polymer admixture, (b) intermixing said aqueous polymeradmixture, in an amount effective for dewatering, with a suspension ofdispersed solids, and (c) dewatering said suspension of dispersedsolids.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0035] The aqueous dispersions of the instant invention contain a firstcationic water-soluble or water-swellable polymer, preferably avinyl-addition polymer. The cationic charge of said first cationicpolymer may vary over a broad range by containing from about 1% to about100% cationic recurring units, preferably about 5% or greater, morepreferably about 10% or greater, even more preferably about 20% orgreater, most preferably about 30% or greater, preferably about 90% orless, more preferably about 80% or less, most preferably about 70% orless, by mole based on total moles of recurring units in said firstcationic polymer. Cationic recurring units may be formed bypost-reaction of polymer, but are preferably formed by polymerization ofcationic monomers. Cationic monomers may include any cationic monomer,including diallyldialkylammonium halide, cationic (meth)acrylates, andcationic (meth)acrylamides commonly used in preparing water-solublepolymers, preferably diallyldimethylammonium halide, as well as acid andquaternary salts of dialkylaminoalkyl(alk)acrylate anddialkylaminoalkyl(alk)acrylamide. Cationic recurring units may be formedby the polymerization of quatemizable monomers such asdialkylaminoalkyl(alk)acrylate or dialkylaminoalkyl(alk)acrylamide,followed by acidification or quaternization. Most preferably, the firstcationic polymer contains cationic recurring units of the formula (I),preferably formed by polymerization of the corresponding monomers of theformula (II):

[0036] wherein R₁ is H or CH₃, A is O or NH, B is alkylene or branchedalkylene or oxyalkylene having from 1 to 5 carbons, R₂ and R₃ are eachindividually methyl, ethyl, or propyl, R₄ is an alkyl or substitutedalkyl group having from 1 to 10 carbon atoms, or an aryl or substitutedaryl group having from 6 to 10 carbon atoms, and X is a counterion.Preferably, R₂, R₃ and R₄ together contain at least a total of 4 carbonatoms, more preferably at least 5 carbon atoms. In certain preferredembodiments, R₄ is a methyl, ethyl or propyl group. In other preferredembodiments, R₄ is an alkyl or substituted alkyl group having from 4 to10 carbon atoms. In other preferred embodiments, R₄ is benzyl.Preferably, X is chloride, bromide, iodide, methylsulfate, orethylsulfate.

[0037] Monomers which may be copolymerized with the cationic monomersmentioned above may be cationic, nonionic or anionic. Cationic monomersinclude the monomers corresponding to (1) and other cationic monomerssuch as diallydimethylammonium chloride, diallydiethylammonium chloride,etc. Nonionic monomers may include substantially water-soluble monomerssuch as acrylamide, methacrylamide, and N-isopropylacrylamide, ormonomers which are sparingly soluble in water such as t-butylacrylamide,N,N-dialkylacrylamide, diacetone acrylamide, ethyl acrylate, methylmethacrylate, methyl acrylate, styrene, butadiene, ethyl methacrylate,acrylonitrile, etc. and the like. Nonionic monomers may also includemonomers which become charged at low pH, such asdimethylaminoethylacrylate, dimethylaminoethylmethacrylate,diethylaminoethylacrylate, diethylaminoethylmethacrylate andcorresponding acrylamide derivatives such asmethacrylamidopropyldimethylamine. Preferred nonionic monomers areacrylamide, t-butyl acrylamide, methacrylamide, methyl methacrylate,ethyl acrylate and styrene. Anionic monomers may include acrylic acid,2-acrylamido-2-methylpropane sulfonic acid, styrene sulfonic acid, theirsalts and the like. On a mole basis, the polymer contains fewer anionicrecurring units than cationic recurring units so that the polymer,although ampholytic, retains a net positive cationic charge. Preferably,the polymer contains less than 10 mole % anionic recurring units, basedon the total number of recurring units in the polymer.

[0038] The first cationic water-soluble or water-swellable polymer maybe a copolymer and may contain other cationic recurring units ornonionic recurring units. Nonionic recurring units may be formed fromwater-soluble monomers such as N-vinylpyridine, N-vinylpyrrolidone,hydroxyalkyl(meth)acrylates, etc., preferably (meth)acrylamide, or maybe formed from hydrophobic monomers having low water-solubility, so longas the inclusion of the poorly water-soluble, e.g. hydrophobic,recurring units does not render the resulting polymer water-insoluble orwater-nonswellable. The first cationic polymer may contain amounts ofrecurring units of water-soluble non-ionic monomers ranging from 0% toabout 99%, preferably about 10% or greater, more preferably about 20% orgreater, most preferably about 30% or greater; preferably about 90% orless, more preferably about 80% or less, most preferably about 70% orless, by mole based on total moles of recurring units in said polymer.The hydrophobic monomers may be hydrocarbon monomers e.g. styrene,butadiene, 1-alkene, vinyl cyclohexane, etc., other vinyl monomers suchas vinyl halide, other primarily aliphatic or aromatic compounds withpolymerizable double bonds, or monomers with only moderatewater-solubility such as acrylonitrile. Preferably, the hydrophobicmonomers are alkyl (alk)acrylates or aryl (alk)acrylates in which thealkyl or aryl groups contain about 1-12 carbon atoms, such as methyl(meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl(meth)acrylate, hexyl (meth)acrylate, ethylhexyl (meth)acrylate,isoalkyl (meth)acrylate, cyclohexyl (meth)acrylate, or aromatic(meth)acrylate, or alkyl or aryl (alk)acrylamides in which the alkyl oraryl groups contain about 1-12 carbon atoms, such as methyl(meth)acrylamide, ethyl (meth)acrylamide, t-butyl (meth)acrylamide,dimethyl (meth)acrylamide, hexyl (meth)acrylamide, ethylhexyl(meth)acrylamide, isoalkyl (meth)acrylamide, cyclohexyl(meth)acrylamide, or aromatic (meth)acrylamide. The first cationicwater-soluble or water-swellable polymer may contain amounts ofhydrophobic non-ionic recurring units ranging from 0% to about 15%,preferably about 2% to about 10%, by mole based on total moles ofrecurring units in said polymer. Although hydrophobic recurring unitsmay be dilutive of the polymer effect in certain applications, inclusionin controlled amounts may advantageously affect a particularcharacteristic of the aqueous dispersion, e.g. solubility rate, bulkviscosity, cost, ease of processing, performance, etc. Depending on thespecific embodiment, it may be preferable for the polymer to be devoidof hydrophobic recurring units, or to contain chosen amounts ofhydrophobic recurring units so as to achieve an advantageous effectwithout disadvantageously increasing the dilutive effect.

[0039] The first vinyl-addition monomer of the formula (II) may becopolymerized with a second vinyl-addition monomer of the formula (II)wherein R₁ is H or CH₃, A is O or NH, B is an alkylene or branchedalkylene or oxyalkylene group having from 1 to 5 carbons, X is acounterion, and R₂, R₃ or R₄ is selected from the group consisting ofC₄-C₁₀ alkyl, benzyl, and C₂H₄C₆H₅. In this case, the amount of thefirst monomer is preferably greater than the amount of the secondmonomer on a molar basis. Also, if R₂, R₃ and R₄ in the first monomer ofthe formula (II) together contain a total of 3 carbon atoms, then themonomers are preferably free of hydrophobic monomers.

[0040] Likewise, if the first polymer contained in an aqueous dispersionof the instant invention is comprised of a first recurring unit of theformula (I) as set forth above, and is further comprised of a secondrecurring unit of formula (I) wherein R₁ is H or CH₃, A is O or NH, B isan alkylene or branched alkylene or oxyalkylene group having from 1 to 5carbons, X is a counterion, and R₂, R₃ or R₄ is selected from the groupconsisting of C₄-C₁₀ alkyl, benzyl, and C₂H₄C₆H₅, then the amount of thefirst recurring unit is preferably greater than the amount of the secondrecurring unit on a molar basis. Also, if R₂, R₃ and R₄ in the firstrecurring unit of the formula (I) together contain a total of 3 carbonatoms, then the first polymer is preferably devoid of hydrophobicrecurring units.

[0041] The amount of the first cationic water-soluble or water-swellablepolymer in the aqueous dispersion is as high as practicable, taking intoaccount the effect of high solids on bulk viscosity, preferably about 5%or greater, more preferably about 10% or greater, most preferably about20% or greater, by weight based on the total weight of the aqueousdispersion. Generally, the solids are not increased above an amountwhich increases the bulk viscosity to an impractical level. Practically,the amount of first cationic polymer in the aqueous dispersion is about75% or less, preferably about 60% or less, more preferably about 50% orless, by weight based on total weight. The weight average molecularweight of the first cationic polymer in the aqueous dispersion is notcritical and depends on the application, but is generally higher thanabout 1,000,000, preferably greater than about 2,000,000, morepreferably greater than about 5,000,000, and most preferably greaterthan about 10,000,000. Molecular weights of polymers are weight averageand may be determined by means known to those skilled in the art,preferably by light scattering.

[0042] The aqueous dispersions of the instant invention are generallycomprised of a discontinuous phase of small aqueous droplets, containingpolymer that is comprised predominately of the first cationicwater-soluble or water-swellable polymer, that are dispersed in theaqueous continuous phase, although of course minor amounts of said firstpolymer may be found in the continuous phase. Thus, the first cationicwater-soluble or water-swellable polymer generally constitutes more than50%, preferably more than 75%, of the polymer in a typical small aqueousdroplet. The amount of first cationic polymer in the discontinuous andcontinuous phases may be determined by known analytical techniques e.g.Raman microscopy. Although large aqueous droplets or gel particles maybe formed by adding dry or gel polymer to the other components as inU.S. Pat. No. 4,673,704 and EP 0 170 394 A2, the aqueous dispersions ofthe instant invention are preferred because it is generally moredesirable for the first cationic polymer to be in the form of smalldroplets which are generally held suspended in a continuous matrix ofthe aqueous phase and do not generally rest substantially in contactwith one another. Although aqueous dispersions prepared bypolymerization of monomers as herein described may sometimes have anaverage droplet size of about 30 microns or more, the average dropletsize is generally less than about 30 microns, preferably less than 20microns, more preferably about 15 microns or less. Droplet size of anon-spherical droplet is the length along a major axis. Droplet size andshape tend to be a function of reactor conditions such as stirring rate,reactor configuration, type of stirrer, etc. Preferably, the size of thedroplets is chosen by carrying out the polymerization in the presence ofone or more insoluble polymeric seeds, said polymeric seeds beinginsoluble in an aqueous solution having the same inorganic saltconcentration as said aqueous dispersion.

[0043] The aqueous dispersions of the instant invention contain a secondwater-soluble polymer, preferably a vinyl-addition polymer, that isdifferent from and, preferably, incompatible with, said firstwater-soluble or water-swellable cationic polymer. The second polymer isdifferent from the first polymer when it can be distinguished from thefirst polymer on the basis of a particular physical characteristic e.g.chemical composition, charge, molecular weight, molecular weightdistribution, distribution of recurring units along the polymer chain,etc., by known characterization methods e.g. spectroscopy,chromatography, etc. The second polymer is incompatible with the firstpolymer when solutions of the two polymers, at the concentrationspresent in the aqueous dispersion, do not form a homogenous mixture whenblended, or do not form a homogenous mixture when one polymer is formedby polymerization of monomers in the presence of the other polymer.

[0044] The second, preferably cationic, water-soluble polymer in theaqueous dispersion of the instant invention is generally dissolved inthe aqueous continuous phase, although of course minor amounts may befound in the discontinuous phase. The amount of second polymer in thediscontinuous and continuous phases may be determined by knownanalytical techniques e.g. Raman microscopy. The second polymer may beany nonionic water-soluble polymer, preferably a polyalkyleneoxide, apolyvinylalcohol, polyvinylpyridine, polyvinylpyrollidone,polyhydroxylalkyl(alk)acrylate, etc., most preferablypoly(meth)acrylamide. Even more preferably, the second water-solublepolymer is cationic. The second polymer may be any cationic polymer, andthe charge may vary over a broad range by containing about 1% to about100% cationic recurring units, preferably about 10% or greater, morepreferably about 20% or greater, even more preferably about 30% orgreater, by mole based on total moles of recurring units in the polymer.Although in some cases the second cationic polymer may contain about 70%or less, or even about 50% or less, of cationic recurring units,preferably the second polymer is predominately cationic i.e. containsmore than 50% cationic recurring units, by mole based on total moles ofrecurring units in the polymer; most preferably about 80% or greater ofrecurring cationic units, same basis. Cationic recurring units may beformed by polymerization of cationic monomers or by post-reaction ofpolymer as above, and may be a copolymer and may contain other cationicrecurring units or nonionic recurring units as above. Preferred secondcationic water-soluble polymers contain recurring units ofdiallyldialkylammonium halide, methyl chloride quaternary salt ofdialkylaminoalkyl(alk)acrylate, dimethyl sulfate quaternary salt ofdialkylaminoalkyl(alk)acrylate, methyl chloride quaternary salt ofdialkylaminoalkyl(alk)acrylamide, or dimethyl sulfate quaternary salt ofdialkylaminoalkyl(alk)acrylamide. Especially preferred second cationicwater-soluble polymers contain recurring units ofdiallyldimethylammonium chloride, methyl chloride quaternary salt ofdimethylaminoethyl(meth)acrylate, or dimethyl sulfate quaternary salt ofdimethylaminoethyl(meth)acrylate. One or more second cationic polymersmay be used. Other cationic polymers and copolymers such as polyaminesand condensation polymers made from monomers such as epichlorohydrin anddimethylamine are also useful in the practice of this invention.Polyamines are generally well-known and include reaction products ofmono-, di- and/or triamines with epihalohydrin and/or di- ortrihaloalkane, where the ratio of the various constituents may bemanipulated to give a polyamine product having the desired molecularweight.

[0045] Depending on the application, it may be preferable for the secondpolymer to be cationic in order to maximize the cationic charge densityof the aqueous dispersion. Also, for embodiments which contain salt, itmay be preferable for the second polymer to be cationic because cationicpolymers are often more soluble in salt solution than nonionic polymers.

[0046] The amount of the second, preferably cationic, water-solublepolymer in the aqueous dispersion is generally chosen to control aqueousdispersion properties e.g. performance, bulk viscosity, charge,molecular weight, solubility rate, physical stability, e.g. settling,etc. Generally, the amount of said second polymer is about 5% orgreater, preferably about 10% or greater, more preferably about 20% orgreater, most preferably about 30% or greater, by weight based on theamount of first cationic water-soluble polymer. Practically, the amountof second water-soluble polymer in the aqueous dispersion is 100% orless, preferably about 80% or less, more preferably about 50% or less,by weight based on the amount of first cationic water-soluble polymer.In certain preferred embodiments, the amounts of the first and secondpolymers are effective to form an aqueous dispersion. In someembodiments, an aqueous dispersion is not formed in the absence of thesecond polymer, and a homogeneous composition is obtained instead.Practically, the amount of first and second polymer may be found byroutine experimentation, and different amounts will ordinarily be useddepending on the identity of the first and second polymers, the totalpolymer solids level, the bulk viscosity, cost, ease of production,product performance, etc.

[0047] The weight average molecular weight of the second water-solublepolymer in the aqueous dispersion is also generally chosen to providethe most advantageous effect, e.g. bulk viscosity, performance, cost,etc., but is generally higher than about 10,000, preferably greater thanabout 50,000, more preferably greater than about 500,000, and mostpreferably greater than about 1,000,000. Molecular weights of polymersare weight average and may be determined by means known to those skilledin the art, preferably by light scattering. The second water-solublepolymer is primarily in the continuous phase of the aqueous dispersion,although of course minor amounts may be contained in the disperseddroplets. Preferably, the aqueous dispersions of the instant inventionare heterogeneous compositions in which more than 50%, preferably about75% or more, of the first cationic water-soluble or water-swellablepolymer is in the form of a discontinuous phase of aqueous droplets thatare dispersed in an aqueous solution that is comprised of more than 50%,preferably about 75% or more, of the second, preferably cationic,water-soluble polymer.

[0048] The aqueous dispersions of the instant invention may contain athird water-soluble or water-swellable polymer that is different fromthe first or second polymers. For instance, the third polymer may alsobe contained in droplets dispersed in the aqueous solution, in whichcase it may be described as discussed above for the first cationicpolymer. The third polymer may also be dissolved in the aqueous solutionalong with the second polymer, in which case it may be described asdiscussed above for the second polymer. Preferably, the third polymer iscationic.

[0049] A third aqueous dispersion, containing three or more polymers,may be formed by blending first and second aqueous dispersions of theinstant invention, wherein the first and second aqueous dispersions aredifferent from each other. Blending is generally carried out byintermixing the aqueous dispersions, typically with stirring. Blendingmay be advantageous to achieve a balance of properties exhibited by theindividual aqueous dispersions, e.g. performance, charge, total polymersolids, cost, molecular weight, etc. Surprisingly, in many cases theblends are stable, e.g. remain in the form of aqueous dispersions havinglow bulk viscosity e.g. less than 10,000 centipoise for periods of oneweek or more, even when the salt or second polymer level in the blend isgreatly different from the level needed to obtain a stable product forone or both of the dispersed polymers, if formulated alone. Alsosurprisingly, the bulk viscosity of the blend is often lower than thebulk viscosity of any of the individual aqueous dispersions.

[0050] The molecular weight of the aqueous dispersion, as that term isused herein, is simply the weight average molecular weight of thepolymers contained therein, obtained by subjecting the entire dispersionto a suitable molecular weight characterization technique e.g. lightscattering. Since the aqueous dispersion contains two or more differentpolymers, each of which may have a molecular weight and molecular weightdistribution different from the other(s), the molecular weightdistribution of the aqueous dispersion may be multimodal. The molecularweight of the aqueous dispersion is generally about 1,000,000 orgreater, preferably greater than 2,000,000, more preferably about3,000,000 or greater, most preferably about 5,000,000 or greater.

[0051] In some cases it may be more convenient to characterize theaqueous dispersion in terms of standard viscosity instead of bymolecular weight. As used herein, “standard viscosity” is determined by:diluting an aqueous dispersion with water to form an aqueous admixture(in the case of water-swellable polymers) or solution (in the case ofwater-soluble polymers) having a polymer concentration of about 0.2%;mixing together 8.0 g of this aqueous admixture or solution with 8.6 gof 2M NaCl; and then measuring the viscosity of the resultant mixture at25° C. on a rotating cylinder viscometer e.g. Brookfield Viscometerequipped with a UL adapter at 60 rpm. The standard viscosities of theaqueous dispersions of the instant invention are generally about 1.5centipoise or greater, preferably about 1.8 centipoise or greater, morepreferably about 2.0 centipoise or greater, most preferably about 2.5centipoise or greater, depending on the application.

[0052] The aqueous dispersions of the instant invention may also beintermixed with water-in-oil emulsions or microemulsions ofwater-soluble polymers to form compositions which, though they containoil, contain proportionately less oil than the water-in-oil emulsions ormicroemulsions from which they are derived. Consequently, thesecompositions may advantageously produce less secondary pollution, havelower flammability, etc.

[0053] Certain embodiments of the instant invention require salt.Effective amounts of salt tend to reduce the bulk viscosity of theaqueous dispersion. The salt may be any inorganic salt, preferably akosmotropic salt e.g. a chloride, sulfate, phosphate, orhydrogenphosphate salt, more preferably ammonium sulfate, sodiumchloride, and sodium sulfate, most preferably sodium sulfate andammonium sulfate. The counterion may be any counterion, e.g. Group IAand Group IIA metal ions, ammonium, etc., preferably ammonium, sodium,potassium and magnesium. Mixtures of salts may be used, and the amountof salt may be chosen to achieve a desirable bulk viscosity or any otherdesirable effect. Since the salt may have a dilutive effect, in certainpreferred embodiments the salt is only added in amounts so as to achievea homogeneous composition in the absence of the second water-solublepolymer. In these embodiments, the aqueous dispersion is not formed bythe action of the salt, but by the interaction of the first and secondpolymers. Effective or viscosity-reducing amounts of salt may be foundthrough routine experimentation and are generally chosen to reduce thebulk viscosity without causing precipitation of the polymer. In otherpreferred embodiments, the salt is only added in amounts so as toachieve a homogeneous composition in the absence of the first cationicpolymer. In embodiments where salt is helpful but not necessary, saltlevels may range upwards from 0%, preferably about 3% or greater, mostpreferably about 5% or greater, by weight based on total weight,depending on the upper limit to solubility, because solubility of thesalt in the aqueous dispersion is preferred. In embodiments where saltis necessary, salt levels are chosen to favorably influence productattributes such as cost, bulk viscosity, etc. and may range upwards fromabout 1%, preferably about 3% or greater, most preferably about 5% orgreater, by weight based on total weight, depending on the upper limitto solubility, because solubility of the salt in the aqueous dispersionis preferred. Frequently, no practical effect of the salt is observedabove about 30%, so salt levels are generally about 30% or less,preferably about 25% or less, by weight based on total weight.Practically, the salt level may be determined by routineexperimentation, e.g. balancing the tendency for positive productattributes e.g. lower bulk viscosities resulting from higher saltlevels, against the negative aspects of salt use e.g. cost and dilutiveeffect.

[0054] Surprisingly, it has been discovered that mixtures of chaotropicsalts with kosmotropic salts, or anionic organic salts with kosmotropicsalts, have a tendency to reduce the bulk viscosity of the aqueousdispersion. In many cases, the salt mixture is more effective thaneither salt alone, on a weight basis. Useful chaotropic salts includethiocyanates, perchlorates, chlorates, nitrates, bromides, iodides, andmixtures thereof, preferably sodium thiocyanate and sodium iodide.Useful anionic organic salts include anionic surfactants and anionichydrotropic salts, preferably aryl and substituted aryl sulfonateshaving from 6 to 22 carbons, preferably 6 to 18 carbons, and alkyl andsubstituted alkyl sulfonates having from 2 to 22 carbons, preferably 4to 18 carbons, and mixtures thereof. Especially preferred anionicorganic salts are dialkylsulfosuccinates, diarylsulfosuccinates,benzenesulfonates, benzenedisulfonates, naphthalensulfonates,naphthalenedisulfonates, and mixtures thereof; 1,3-benzendisulfonatesare most preferred. Counterions to the chaotropic and anionic organicsalts may be any typical counterion, e.g. Group IA metal ions, ammonium,etc., preferably ammonium, sodium, and potassium. Effective orviscosity-reducing amounts of chaotropic and anionic organic salts maybe found through routine experimentation and are generally chosen toreduce the bulk viscosity without causing precipitation of the polymer.In certain preferred embodiments, the amounts of chaotropic salt, oranionic organic salt, and kosmotropic salt are chosen such that ahomogeneous composition is obtained in the absence of the secondcationic polymer; i.e. the concentration of the salts is such that thefirst cationic polymer is not precipitated in the absence of the secondcationic polymer. Generally, amounts of chaotropic, or anionic organic,salts are about 10% or less, preferably about 5% or less, and generally0.5% or more, preferably 1% or more, by weight based on total weight. Atvery low chaotropic or anionic organic salt levels, theviscosity-reducing effect of the salt is negligible, whereas the saltmay cause undesirable precipitation or layering at high levels ofincorporation. To achieve a certain bulk viscosity, amounts ofkosmotropic salts used with the chaotropic, or anionic organic salt, aregenerally less than when the kosmotropic salt is used alone, but stillwithin the ranges given above for the use of inorganic or kosmotropicsalts alone.

[0055] The aqueous dispersions of the instant invention generally havelower bulk viscosities than comparable aqueous dispersions. A comparableaqueous dispersion is generally one which is substantially identical inmany functional aspects, but lacks a particular element of the instantinvention. In general, the aqueous dispersions of the instant inventionhave lower bulk viscosities than comparable aqueous dispersions whichhave substantially the same polymer solids, cationic charge level andweight average molecular weight, but which lack an important feature ofthe instant invention e.g. lack a recurring unit of formula (I); lackthe amount of recurring units of formula I found in the aqueousdispersions of the instant invention; not made by a process whichcomprises polymerizing vinyl-addition monomers comprised of at least onemonomer of the formula (II); not made by a process which comprisespolymerizing vinyl-addition monomers comprised of the amount of monomersof the formula (II) used in the processes of the instant invention, etc.For instance, in a composition comprising an aqueous dispersioncomprised of: (a) a discontinuous phase containing polymer that iscomprised predominately of a first cationic water-soluble orwater-swellable polymer having at least one recurring unit of theformula (I), and (b) at least one second water-soluble polymer differentfrom said first polymer, a comparable aqueous dispersion may be onewhich contains the same amount of each component, except the R₂, R₃ andR₄ in the corresponding recurring formula (I) unit of the comparableaqueous dispersion together contain a total of 3 carbon atoms, insteadof the 4 or more carbons in the corresponding recurring unit of formula(I) in the claimed aqueous dispersion.

[0056] Surprisingly, aqueous dispersions having formula (I) recurringunits in which R₂, R₃ and R₄ contain four or, preferably, five carbonsgenerally have bulk viscosities which are dramatically lower than thebulk viscosities of aqueous dispersions that are substantially identicalexcept that R₂, R₃ and R₄ contain only three carbons. The bulk viscosityof aqueous dispersions is typically influenced by e.g. total polymersolids, salt level, polymer type, ratio of first cationic polymer tosecond cationic polymer, etc. as disclosed herein. Although aqueousdispersions having bulk viscosities of about 20,000 centipoise (cps) ormore, or even about 200,000 cps or more may be suitable in certaincircumstances, much lower bulk viscosities are generally preferred forease of handling. Aqueous dispersions having bulk viscosities of about20,000 centipoise (cps) or less, preferably about 10,000 cps or less,more preferably about 8,000 cps or less, even more preferably about5,000 cps or less, most preferably about 2,500 cps or less, may beobtained by the practice of the instant invention. Bulk viscosity may bemeasured by any convenient method known to those skilled in the art,preferably a rotating cylinder viscometer as described in the Examplesbelow.

[0057] Aqueous dispersions are preferred which have as many of thefollowing advantageous attributes as possible: relatively high cationicpolymer solids, preferably 20% or greater, more preferably 25% orgreater, by weight based on total; high molecular weight, preferably2,000,000 or greater, more preferably 5,000,000 or greater; reducedenvironmental impact (low VOC, substantially free of organic solventsand aromatic groups, e.g. aromatic- or benzyl-containing oils orrecurring units); minimal levels of diluents (preferably, 20% or less ofsalt, by weight based on total, and polymer devoid or substantially freeof hydrophobic recurring units); bulk viscosity about 2,000 cps or less;for recurring units based on formula (I), R₂, R₃ and R₄ togethercontaining a total of 5 carbons; and superior or equivalent performance.Products having all of these attributes may be obtained by the practiceof the present invention.

[0058] Aqueous dispersions of water-soluble polymers are preferablyformed by polymerization of the corresponding monomers to form the firstcationic water-soluble polymer, in the presence of at least one secondcationic water-soluble polymer and, in certain embodiments, an inorganicsalt. Polymerization may be effected by any initiating means, includingredox, thermal or irradiating types. Examples of preferred initiatorsare 2,2′-azobis(2-amidino-propane)dihydrochloride (V-50),2,2′-azobis(isobutyronitrile), sodium bromate/sulfur dioxide, potassiumpersulfate/sodium sulfite, and ammonium persulfate/sodium sulfite, aswell as peroxy redox initiators e.g. those disclosed in U.S. Pat. No.4,473,689. Initiator levels are chosen in a known manner so as to createpolymers of the desired molecular weight. Amounts of chain transferagents, e.g. isopropanol, lactic acid, mercaptoethanol, etc. andbranching or crosslinking agents, e.g. methylenebisacrylamide may beadded in a known manner to further adjust the properties of the firstcationic water-soluble polymer. Depending on the production conditions,e.g. types and relative amounts of chain transfer agent and branchingagent, water-swellable or branched, water-soluble polymers may beformed. In general, the use of greater amounts of branching orcrosslinking agent increases the tendency for the product to bewater-swellable instead of water-soluble, and increased amounts of chaintransfer agent tend to reduce molecular weight. When chain transferagent and branching agent are used together, water-swellable productsare more likely to be obtained at high branching agent and low chaintransfer agent levels, whereas branched, water-soluble polymers may beobtained at high chain transfer and low branching agent levels.Components may be added at any time; e.g. all of the monomers may bepresent from the onset of the polymerization, or monomers may be addedduring the course of the polymerization. If salt is used, all of thesalt may be present from the onset of the polymerization, or salt may beadded during the course of the polymerization or after polymerization iscomplete. Likewise, polymerization parameters e.g. temperature and timemay be chosen in a known manner, and may be varied during the course ofthe polymerization. Polymerization is generally effected in the presenceof an inert gas, e.g. nitrogen. Conventional processing aids e.g.chelating agents, sequestrants, pH adjusters, etc. may be added asrequired.

[0059] The aqueous dispersions of the present invention haveadvantageous aspects in that they are preferably substantially free ofdilutive substances such as surfactant, oil, hydrocarbon liquids,organic solvents, etc. Although viscosity-reducing additives e.g.glycerin, glycerol, alcohol, glycol, etc. may be present in the aqueousdispersions, amounts should be 2% or less, more preferably 1% or less,most preferably 0.1% or less, in order to maintain the advantageousproperties of the invention.

[0060] The aqueous dispersions of the instant invention may behomogenous in the absence of a particular component e.g., said secondwater-soluble polymer. Homogenous compositions are generallycharacterized as being clear or translucent, and are not aqueousdispersions because they do not contain dispersed droplets as describedabove. Depending on the embodiment, said first cationic water-solublepolymer or said second cationic water-soluble polymer isdispersion-creating in that aqueous dispersions are not obtained in theabsence of an effective or dispersion-creating amount of the particularcomponent.

[0061] Waters used in the present invention may be from any source, e.g.process water, river water, distilled water, tap water, etc. Preferably,polymerizations are conducted in aqueous solutions that do not containsubstantial amounts of materials which detrimentally affect thepolymerization. Advantageously, the aqueous dispersions of the presentinvention tend to dissolve quickly when diluted with water.

[0062] The aqueous dispersion of the instant invention may be dehydratedto increase the total polymer solids content, or to create substantiallydry products. Any means known in the art e.g. stripping, spray drying,solvent precipitation, etc. may be used to reduce the water content.Surprisingly, partial dehydration may reduce the bulk viscosity of anaqueous dispersion, in spite of the tendency for dehydration to increasepolymer solids. Dehydration may be performed by heating, preferablyunder reduced pressure, although of course excessive heating may bedetrimental to polymer properties. A substantially dry mass of polymermay be obtained by removal of water, and the mass may be comminuted tocreate a powdery, particulate, or granular product.

[0063] Surprisingly, substantially dry polymer products may be obtainedby spray-drying the aqueous dispersions of the instant invention.Although oil-containing polymer emulsions and dispersions have beenspray-dried, see e.g. U.S. patent application Ser. No. 08/668,288 andreferences therein, spray-drying of aqueous dispersions, which aregenerally free of oil and surfactants, has not previously been reported.In accordance with the instant invention, vinyl-additionpolymer-containing aqueous dispersions may be sprayed-dried by asuitable means into a large chamber through which a hot gas is blown,thereby removing most or all of the volatiles and enabling the recoveryof the dried polymer. Surprisingly, the means for spraying the aqueousdispersion into the gas stream are not particularly critical and are notlimited to pressure nozzles having specified orifice sizes; in fact, anyknown spray-drying apparatus may be used. For instance, means that arewell known in the art such rotary atomizers, pressure nozzles, pneumaticnozzles, sonic nozzles, etc. can all be used to spray-dry the aqueousdispersion into the gas stream. The feed rate, feed viscosity, desiredparticle size of the spray-dried product, droplet size of the aqueousdispersion, etc. are factors which are typically considered whenselecting the spraying means. The size and shape of the chamber, thenumber and type of spraying means, and other typical operationalparameters may be selected to accommodate dryer conditions using commonknowledge of those skilled in the art.

[0064] Although closed cycle spray-dryers may be used, open cyclespray-drying systems are preferred. Gas flow may be cocurrent,countercurrent or mixed flow, cocurrent flow being preferred. The hotgas, or inlet gas, may be any gas that does not react or form explosivemixtures with the feed and/or spray-dried polymer. Suitable gases usedas the inlet gas are gases known to those skilled in the art, includingair, nitrogen, and other gases which will not cause undesirable polymerdegradation or contamination, preferably gases containing about 20% orless oxygen, more preferably about 15% or less oxygen. Most preferably,inert gases such as nitrogen, helium, etc. that contain about 5% or lessof oxygen should be used.

[0065] The dried polymer may be collected by various means such as asimple outlet, classifying cone, bag filter, etc., or the polymer may besubjected to further stages of drying, such as by fluid beds, oragglomeration. The means for collecting the dry polymer product is notcritical.

[0066] There are four interrelated operating parameters in the instantspray-drying process: gas inlet temperature, gas outlet temperature,product volatiles and residence time in the dryer. The outlettemperature generally should be about 150° C. or below, preferably about120° C. or below, more preferably less than 100° C., even morepreferably about 95° C. or below, most preferably about 90° C. or below.The outlet temperature is generally about 70° C. or higher, preferablyabout 75° C. or higher. Therefore, outlet temperatures are generallyabout 70° C. to about 150° C., preferably about 70° C. to about 120° C.,more preferably about 70° C. to less than 100°, even more preferablyabout 70° C. to about 95° C., most preferably about 75° C. to about 90°C. Outlet temperatures below about 70° C. may be suitable in certaininstances, though generally this is less preferred. For instance, at thecost of efficiency, spray drying could be carried out at long residencetimes, high gas flow rates and low outlet temperatures. Generally, thedryer should be operated at the lowest possible outlet temperatureconsistent with obtaining a satisfactory product.

[0067] The inlet temperature, the feed rate, and the composition of theaqueous dispersions may all affect outlet temperatures. These parametersmay be varied to provide a desired outlet temperature. Feed rates arenot critical, and generally will vary depending on the size of the dryerand the gas flow rate. Inlet gas temperature is less critical thanoutlet gas temperature, and is generally about 140° C. or above,preferably about 160° C. or above. The inlet gas temperature ispreferably about 200° C. or below and more preferably about 180° C. orbelow. Thus, preferred inlet gas temperature ranges from about 140° C.to about 200° C., more preferably from about 160° C. to about 180° C.Proper inlet gas temperatures tend to avoid product degradation on thehigh side and to avoid inadequate drying on the low side.

[0068] Residence time is a nominal value obtained by dividing the volumeof the dryer by the volumetric gas flow. Residence time is generally atleast about 8 seconds, preferably at least about 10 seconds. Residencetime is generally no more than about 120 seconds, preferably no morethan about 90 seconds, more preferably no more than about 60 seconds,and most preferably no more than about 30 seconds. Therefore, thegeneral range of residence time is about 8 to about 120 seconds,preferably about 10 to about 90 seconds, more preferably about 10 toabout 60 seconds, and most preferably about 10 to about 30 seconds. Itis known to those skilled in the art that longer residence times are tobe expected when larger dryers are used or when the dryer is run in aless efficient manner. For instance, at the cost of efficiency, longerresidence times would be expected at very low inlet temperatures andslow gas flow rates. As a practical matter, the residence times usefulin the present invention may vary from the values described above,depending on the size and type of spray dryer used, the efficiency atwhich it is operated, and other operational parameters. Thus, residencetimes specified herein may be modified to accommodate dryer conditionsusing common knowledge of those skilled in the art.

[0069] When produced according to the spray drying processes disclosedherein, polymer particles of the instant invention are generally about10 microns or greater in diameter, preferably about 40 microns orgreater, more preferably about 100 microns or greater, most preferablyabout 200 microns or greater. It is preferred that the polymer particlesbe non-dusting. Dusting and flow problems are typically exacerbated whenthe polymer particles are small, so larger polymer particles aregenerally desirable. However, very large particles may dissolve moreslowly. Therefore, it is generally desirable for the polymer particlesto be about 1200 microns or less in diameter, preferably about 800microns or less in diameter, more preferably about 600 microns or less,most preferably about 400 microns or less. Generally, at least about 90%of the polymer particles range in size from about 10 microns to about1200 microns, preferably at least about 95%, more preferably at leastabout 98%. The size of the polymer particles can be varied somewhat byaltering the operational parameters e.g. spray configuration, aqueousdispersion viscosity, feed rate, etc. Particles may be substantiallyspherical or non-spherical; “diameter” of a non-spherical particle isthe dimension along a major axis.

[0070] Although in some cases the polymer particles are hollow, porousstructures having at least one opening in their walls, it has beendiscovered that these features are not always necessary in order toobtain particles having desirable properties e.g. fast dissolutiontimes. In many cases, the spray-drying parameters e.g. nozzle type,nozzle size, outlet temperature, etc. needed to produce particles thatare hollow, porous structures having at least one opening in their wallsare inconvenient or uneconomical, and it is advantageous to produceparticles that lack some or all of these features.

[0071] The particles formed by the spray-drying processes of the instantinvention may be screened to remove an oversize or undersize fraction.Oversize particles may be fragmented by e.g. grinding, whereasundersized particles are generally agglomerated. Sizes may be determinedby methods known to those skilled in the art e.g. sieving, screening,light scattering, microscopy, microscopic automated image analysis, etc.

[0072] Surprisingly, the bulk densities of the spray-dried polymerparticles of the instant invention are generally greater than the bulkdensities of dry polymers prepared by precipitation of e.g. water-in-oilemulsions of the same polymer. Polymer particles having greater densitymay be advantageous because they occupy a smaller volume, resulting ine.g. lower shipping and storage costs. Whereas the densities ofprecipitated polymers are usually less than about 0.35 grams per cubiccentimeter (g/cc), the bulk densities of the spray-dried polymerparticles of the instant invention are generally about 0.35 g/cc orgreater, preferably about 0.4 g/cc or greater, more preferably about0.45 g/cc or greater, most preferably about 0.50 g/cc or greater. Thebulk densities of the spray-dried polymer particles of the instantinvention are generally about 1.1 g/cc or less, preferably about 1.0g/cc or less, more preferably about 0.95 g/cc or less, most preferablyabout 0.90 g/cc or less. Therefore, the bulk densities of thespray-dried polymer particles of the instant invention generally rangefrom about 0.35 to about 1.1 g/cc, preferably about 0.4 to about 1.0g/cc, more preferably about 0.45 to about 0.95 g/cc, most preferablyabout 0.50 to about 0.90 g/cc.

[0073] Under the conditions of drying set forth herein, the polymerparticles produced by the processes described herein are substantiallydry. As used to describe the polymer produced herein, “substantiallydry” generally means that the polymer contains about 12% or lessvolatiles, preferably about 10% or less by weight, based on the weightof the spray dried polymer. The polymer generally contains about 2% ormore volatiles, preferably about 5% or more, by weight based on totalweight, and most preferably contains from about 8% to about 10%volatiles by weight, same basis. The volatiles are measured bydetermining the weight loss on drying the polymer product at about 105°C. for about 30 minutes.

[0074] It has also been discovered that agglomeration of the polymerparticles of the instant invention may improve the flow properties anddissolution times of the polymers. Agglomeration is a known process forincreasing particle size and various methods for agglomerating particlesare known to those skilled in the art, e.g. “Successfully UseAgglomeration for Size Enlargement,” by Wolfgang Pietsch, ChemicalEngineering Progress, April 1996, pp. 29-45; “Speeding up ContinuousMixing Agglomeration with Fast Agitation and Short Residence Times,” byPeter Koenig, Powder and Bulk Engineering, February 1996, pp. 67-84.Known agglomeration methods such as natural agglomeration, mechanicalagglomeration, tumble or growth agglomeration, pressure agglomeration,binderless agglomeration, agglomeration with binders, etc. may be usedto agglomerate the polymer particles of the instant invention.Agglomeration may optionally be followed by drying e.g. fluid beddrying, to remove binder e.g. water. Pressure agglomeration ispreferred, and mechanical agglomeration using a water binder, followedby fluid bed drying is most preferred.

[0075] The agglomerates formed by agglomerating the polymer particles ofthe instant invention tend to have improved flow properties and fasterdissolution times when compared to the unagglomerated polymer particles.Preferably, the agglomerates are non-dusting. Typically, about 90% ofthe agglomerates of the instant invention have an agglomerate size ofabout 120 microns or greater, preferably about 160 microns or greater,more preferably about 200 microns or greater, most preferably about 300microns or greater. Generally, about 90% of the agglomerates have anagglomerate size of about 1500 microns or less, preferably about 1200microns or less, more preferably about 1100 microns or less, mostpreferably about 1000 microns or less. Thus, about 90%, preferably 95%,of the agglomerates have a size in the range of about 120 to about 1500microns, preferably about 160 microns to about 1200 microns, morepreferably about 200 microns to about 1100 microns, most preferablyabout 300 microns to about 1000 microns Usually, at least about 5% ofthe agglomerates, preferably at least about 10%, most preferably atleast about 15%, are larger than about 900 microns. The agglomeratesformed by agglomerating the spray-dried particles of the instantinvention may be screened to remove an oversize or undersize fraction.Preferably, agglomerates larger than about 1200 microns and smaller thanabout 175 microns are removed by e.g. screening. Oversize agglomeratesare generally fragmented by e.g. grinding, whereas undersizedagglomerates are generally recycled into the agglomerator.

[0076] The bulk density values of the agglomerates of the instantinvention tend to be lower than the bulk density values of thespray-dried particles from which they are formed. The bulk densities ofthe agglomerates of the instant invention are generally about 0.35 g/ccor greater, preferably about 0.4 g/cc or greater, more preferably about0.45 g/cc or greater, most preferably about 0.50 g/cc or greater. Thebulk densities of the agglomerates of the instant invention aregenerally about 1.0 g/cc or less, preferably about 0.95 g/cc or less,more preferably about 0.90 g/cc or less, most preferably about 0.85 g/ccor less. Therefore, the bulk densities of the agglomerates of theinstant invention generally range from about 0.35 to about 1.0 g/cc,preferably about 0.4 to about 0.95 g/cc, more preferably about 0.45 toabout 0.90 g/cc, most preferably about 0.50 to about 0.85 g/cc.

[0077] In order to obtain agglomerates of a preferred size, it ispreferred that the polymer particles themselves be of such a size thatthey are agglomerable. Agglomeration obviously tends to multiply theaverage particle size, so that it is frequently easier to cause largeincreases in particle size than it is to cause small increases inparticle size. Therefore, to produce agglomerates of a preferred size orsize range, it is generally preferred to agglomerate particles that aremuch smaller than the desired agglomerate size, rather than particlesthat are only slightly smaller. Agglomerable particles are generallythose that may be conveniently agglomerated to produce agglomerateshaving a preferred size. It is possible, but less preferred, toagglomerate larger particles to produce agglomerates that are largerthan desired, then remove the oversize agglomerates as described above.

[0078] The substantially dry polymer particles and agglomerates of thepresent invention are generally comprised of the polymer that wascontained in the aqueous dispersion that was spray-dried, as discussedhereinabove.

[0079] Spray-drying of the aqueous dispersions of the instant inventionis advantageous because typically 90% or greater, preferably 95% orgreater, most preferably substantially all, of the resultant spray-driedpolymer particles each individually contains two or more water-solubleor water-swellable vinyl-addition polymers, so that stratificationeffects may be minimized. Stratification may occur when two differentdry polymers having differing particle sizes or particle sizedistributions are blended together because of the tendency for thelarger particles to settle towards the bottom of the container.Stratification on storage may affect blend product performance as thetop of the container tends to become enriched in the polymer having thesmaller particle size. For obvious reasons, changes in productperformance as a function of storage depth are to be avoided, and it isgenerally preferred that each polymer in a blend be of similar particlesize, see e.g. EP 479 616 A1 and U.S. Pat. No. 5,213,693. A dry blend ofthe two different polymers is likely to exhibit greater stratificationthan a dry blend obtained by spray-drying the instant aqueousdispersions because the majority of the spray-dried polymer particles ofthe instant invention each individually contains two or morewater-soluble or water-swellable vinyl-addition polymers. Surprisingly,the spray-dried aqueous dispersions of the instant invention tend todissolve faster than polymers obtained by spray-drying conventionalwater-in-oil emulsions of similar polymers.

[0080] A suspension of dispersed solids may be dewatered by a methodwhich comprises (a) intermixing an effective amount of an aqueousdispersion of polymers, or aqueous admixture thereof, with a suspensionof dispersed solids, and (b) dewatering said suspension of dispersedsolids. Substantially dry polymers derived from the aqueous dispersionsof the instant invention as described above may also be used to dewatersuspended solids. For instance, a suspension of dispersed solids may bedewatered by a method which comprises (a) intermixing an effectiveamount of a substantially dry water-soluble or water-swellable polymer,or aqueous admixture thereof, with a suspension of dispersed solids, and(b) dewatering said suspension of dispersed solids. Preferably, anaqueous admixture of the dry polymer or aqueous dispersion is preparedby intermixing the dry polymer or aqueous dispersion with water, morepreferably by dissolving the dry polymer or aqueous dispersion in waterto form a dilute polymer solution. Effective amounts of dry polymer oraqueous dispersion are determined by methods known in the art,preferably by routine laboratory or process experimentation.

[0081] Examples of suspensions of dispersed solids which may bedewatered by means of the instant invention are municipal and industrialwaste dewatering, clarification and settling of primary and secondaryindustrial and municipal waste, potable water clarification, etc.Because of the advantageous aspects of the invention e.g. substantiallyoil-free, minimum amounts of inactive diluents, little or no surfactant,etc., the polymers may be especially well-suited to situations wherepart or all of the dewatered solids or clarified water is returned tothe environment, such as sludge composting, land application of sludge,pelletization for fertilizer application, release or recycling ofclarified water, papermaking, etc. Other applications which may benefitfrom the advantageous aspects of the instant inventions include soilamendment, reforestation, erosion control, seed protection/growth, etc.,where the aqueous dispersion or dry polymer, preferably an aqueousadmixture thereof, is advantageously applied to soil.

[0082] Other examples of suspensions of dispersed solids which may bedewatered by means of the instant invention are found in the papermakingarea, e.g. the aqueous dispersions or dry polymer may be used asretention aids, drainage aids, formation aids, washer/thickener/drainageproduction aid (DNT deink application), charge control agents,thickeners, or for clarification, deinking, deinking process waterclarification, settling, color removal, or sludge dewatering. Thepolymers of the instant invention may also be used in oil fieldapplications such as petroleum refining, waster clarification, wastedewatering and oil removal.

[0083] Dewatering and clarification applications for the aqueousdispersions and dry polymers of the instant invention may also be foundin the food processing area, including waste dewatering, preferablywaste dewatering of poultry beef, pork and potato, as well as sugardecoloring, sugar processing clarification, and sugar beetclarification.

[0084] Mining and mineral applications for the aqueous dispersions anddry polymers of the instant invention include coal refuse dewatering andthickening, tailings thickening, and Bayer process applications such asred mud settling, red mud washing, Bayer process filtration, hydrateflocculation, and precipitation.

[0085] Biotechnological applications for the aqueous dispersions and drypolymers of the instant invention include dewatering and clarificationof wastes and preferably, dewatering and clarification of fermentationbroths.

[0086] The aqueous dispersions of the instant invention may be employedin the above applications alone, in conjunction with, or serially with,other known treatments.

[0087] All patents, patent applications, and publications mentionedabove are hereby incorporated herein by reference. Unless otherwisespecified, all percentages mentioned herein are understood to be on aweight basis.

[0088] The Standard Viscosity (SV) values in the following Examples weredetermined by mixing together 8.0 g of a 0.2 wt. % polymer solution inwater and 8.6 g of 2M NaCl, then measuring the viscosity of theresultant solution at 25° C. on a Brookfield Viscometer equipped with aUL adapter at 60 rpm. Molecular weights were determined by highperformance size exclusion chromatography using a light scatteringdetector.

[0089] The bulk density of polymer particles and agglomerates wasdetermined by adding the particles or agglomerates to a suitablepreweighed measuring container and “tapping” or slightly agitating thecontainer to cause the particles or agglomerates to settle. The volumeof the polymer was then read from the measuring container, the measuringcontainer weighed, and the bulk density calculated in units of grams percubic centimeter (g/cc).

EXAMPLE 1

[0090] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and a nitrogen inlet tube was charged with 17.10 partsdeionized water and 9 parts of a 40% aqueous solution of the polymerobtained by polymerizing the methyl chloride quaternary salt ofdimethylaminoethylmethacrylate (poly(DMAEM.MeCl)), weight averagemolecular weight about 200,000. After completion of dissolution, 7.08parts of a 53.64% aqueous solution of acrylamide (AMD), and 14.56 partsof a 72.80% solution of the dimethyl sulfate salt ofdiethylaminoethylacrylate (DEAEA.DMS) were added and mixed. To thismixture, 8.1 parts ammonium sulfate, 0.7 parts citric acid, and 2.02parts of a 1% solution of chelant ethylenediaminetetraacetic acidtetrasodium salt (EDTA) were added and mixed. The pH of the mixture wasabout 3.3. The vessel was sealed and sparged with nitrogen for 30minutes, and then polymerization was started by adding 1.44 parts of 1%aqueous solution of 2,2′-azobis(2-amidino-propane)dihydrochloride(V-50). The reaction mixture was heated to 40° C. for 2 hours and thenraised to 50° C. and held for an additional 8 hours. The conversion wasgreater than 99%. A stable fluid aqueous dispersion was obtained. Thebulk viscosity (BV) of the dispersion was 2250 centipoise (cps) showingpreferable fluidity as measured with a Brookfield Viscometer, No. 4spindle, 30 rpm at 25° C. The dispersion was dissolved to give astandard viscosity (SV) of 2.56 cps.

EXAMPLES 2-8

[0091] Additional aqueous dispersions were prepared in the same manneras Example 1, showing the effect of various polymer and ammonium sulfatesalt levels on bulk viscosity as shown in Table 1. TABLE 1 FIRST SECONDPOLY- POLY- Ex- MER MER ample % TOTAL % % % SV No. SOLIDS SOLIDS SOLIDSSALT BV (cps) (cps) 1 30 24 6 13.5 2,250 2.56 2 30 24 6 12.5 6,600 2.2 330 24 6 13 6,000 2.37 4 30 24 6 13.5 2,960 2.3 5 30 24 6 13.5 2,300 2.356 30 25 5 13.5 2,640 2.61 7 30 24 6 14 3,470 2.39 8 30 24 6 15 7,0802.17

EXAMPLE 9

[0092] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and a nitrogen inlet was charged with 72.60parts of deionized water and 30.8 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 222,600. Afterdissolution was complete, 24.37 parts of a 53.33% aqueous solution ofacrylamide and 45.93 parts of a 79% aqueous solution of DEAEA.DMS wereadded and mixed. To this mixture, 31.9 parts ammonium sulfate, 2.57parts citric acid, and 6.9 parts of 1% solution of EDTA were added andmixed. The pH of the mixture was about 3.3. The vessel was sealed andsparged with nitrogen for 30 minutes, and then polymerization wasstarted by adding 4.93 parts of 1% solution of V-50. The reactionmixture was heated to 40° C. for 2 hours and then raised to and held at50° C. for 4 hours. The overall conversion was greater than 99%. Astable fluid aqueous dispersion was obtained. The bulk viscosity of thisdispersion was about 1460 cps showing preferable fluidity as measuredwith a Brookfield Viscometer, No. 4 spindle, 30 rpm at 25° C. Thedispersion was dissolved to give a SV of 2.40 cps.

EXAMPLES 10-33

[0093] Additional aqueous dispersions were prepared in the same manneras Example 9 demonstrating the effect of total polymer solids, ratio offirst cationic to second cationic polymer, second cationic polymermolecular weight, and ammonium sulfate salt level on the bulk viscosity(BV) of the aqueous dispersion, as shown in Table 2. TABLE 2 FIRSTSECOND SECOND EXAMPLE % TOTAL POLYMER POLYMER POLYMER % NO. SOLIDS %SOLIDS % SOLIDS MW SALT BV (cps) SV (cps)  9 28 22.4 5.6 222,600 14.51,460 2.40 10 28 22.4 5.6 194,000 14.5 2,250 2.52 11 28 22.4 5.6 199,30014.5 1,440 2.52 12 28 22.4 5.6 172,870 14.5 2,940 2.61 13 28 22.4 5.6221,500 14.5 1,970 2.52 14 28 22.4 5.6 159,000 14.5 2,740 2.59 15 2822.4 5.6 145,000 14.5 2,920 2.65 16 28 22.4 5.6 199,300 14.5 2,150 2.8617 30 24 6 242,900 13.5 2,620 2.49 18 30 24 6 230,600 13.5 3,710 2.4 1930 24 6 230,600 14 2,200 2.39 20 30 24 6 230,600 14.5 1,800 2.54 21 3024 6 230,600 15 3,260 2.49 22 28 22.4 5.6 230,600 15   982 2.49 23 2822.4 5.6 230,600 15.5   900 2.45 24 28 23.5 4.5 230,600 15.5 1,380 2.7725 27 22.66 4.34 230,600 15.5 1,600 2.61 26 27 22.66 4.34 230,600 161,770 2.82 27 30 24 6 230,600 14.5 1,770 2.43 28 28 22.4 5.6 230,60015.5 1,820 2.56 29 28 22.4 5.6 230,600 16 3,120 2.44 30 28 23 5 230,60015 1,620 2.5 31 28 23 5 230,600 15.5   962 2.67 32 28 23 5 230,600 161,500 2.59 33 28 22.4 5.6 230,600 15.5 1,260 2.51

EXAMPLE 34

[0094] This polymerization was carried out in the same manner as Example9, except that a poly(DMAEM.MeCl) having a weight average molecularweight of about 395,000 was used. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of this aqueous dispersion was about 5100cps showing preferable fluidity as measured with a BrookfieldViscometer, No. 4 spindle, 30 rpm at 25° C. The dispersion was dissolvedto give a SV of 2.35 cps.

EXAMPLE 35

[0095] This polymerization was carried out in the same manner as Example34, expect that 2.46 parts of 10% glycerol solution was added.Polymerization proceeded smoothly. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of this dispersion was about 3700 cps asmeasured with a Brookfield Viscometer, No. 4 spindle, 30 rpm at 25° C.showing improved fluidity. The bulk viscosity was greatly reducedrelative to Example 34, demonstrating the viscosity-reducing effect ofthe glycerol additive. The dispersion was dissolved to give a SV of 2.35cps.

EXAMPLE 36

[0096] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 39.73parts deionized water and 30.1 parts of 41% poly(DMAEM.MeCl), weightaverage molecular weight about 395,000. After completion of dissolution,23.77 parts of a 53.57% aqueous solution of acrylamide, 45.20 parts ofan 80% aqueous solution of DEAEA.DMS and 38.7 parts of 1% aqueoussolution of tertiary butyl acrylamide were added and mixed. To thismixture, 49.28 parts ammonium sulfate, 2.57 parts citric acid, and 3.45parts of 2% EDTA were added and mixed. The pH of the mixture was about3.3. The vessel was sealed and sparged with nitrogen for 30 minutes, andthen polymerization was started by adding 2.46 parts of 2% V-50. Thereaction mixture was raised to 40° C. for 2 hours and then raised to 50°C. for an additional 4 hours. The overall conversion was greater than99%. A stable fluid aqueous dispersion was obtained. The bulk viscosityof this aqueous dispersion was about 1900 cps as measured with aBrookfield Viscometer No. 4 spindle, 30 rpm at 25° C., showing improvedfluidity compared to Example 34 and demonstrating the effect ofincorporating hydrophobic recurring units of tertiary butyl acrylamide.The aqueous dispersion was dissolved to give a SV of 2.32 cps.

EXAMPLE 37

[0097] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 78.84parts deionized water and 30.1 parts of 41% poly(DMAEM.MeCl), weightaverage molecular weight about 395,000. After completion of dissolution,20.95 parts of a 53.57% aqueous solution of acrylamide, 42.73 parts of a80% aqueous solution of DEAEA.DMS and 4.84 parts of a 80% aqueoussolution of the benzyl chloride quaternary salt of dimethylaminoethylacrylate (DMAEA.BzCl) were added and mixed. To this mixture, 49.28 partsammonium sulfate, 2.57 parts citric acid, and 3.45 parts of 2% EDTA wereadded and mixed. The pH of the mixture was about 3.3. The vessel wassealed and sparged with nitrogen for 30 minutes, and then polymerizationwas started by adding 2.46 parts of 2% V-50. The reaction mixture wasraised to 40° C. for 2 hours, and then raised to and held at 50° C. for4 hours. The overall conversion was greater than 99%. A stable fluidaqueous dispersion was obtained. The bulk viscosity of this dispersionwas about 3840 cps as measured with a Brookfield Viscometer No. 4spindle, 30 rpm at 25° C. showing preferable fluidity. The dispersionwas dissolved to give a SV of 2.14 cps.

EXAMPLE 38

[0098] A suitable vessel with an external jacket for heating or coolingwas equipped with a mechanical stirrer, reflux condenser, thermocoupleand nitrogen inlet tube. The vessel was charged with 294.47 partsdeionized water and 117.60 parts of 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 210,000. Aftercompletion of dissolution, 94.03 parts of a 52.77% aqueous solution ofacrylamide and 173.18 parts of an 80% aqueous solution of DEAEA.DMS wereadded and mixed. To this mixture, 130.20 parts ammonium sulfate, 9.83parts citric acid, and 13.17 parts of 2% EDTA were added and mixed. ThepH of the mixture was about 3.3. The vessel was sealed and sparged withnitrogen for 30 minutes, and then polymerization was started by adding7.53 parts of 1% V-50. The reaction mixture was heated to 40° C. for 2hours and then raised to and held at 50° C. for 4 hours. The overallconversion was greater than 99%. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of this dispersion was about 760 cps asmeasured with a Brookfield Viscometer No. 4 spindle, 30 rpm at 25° C.showing preferable fluidity. The dispersion was dissolved to give a SVof 2.52 cps.

EXAMPLE 38A

[0099] A suitable vessel with an external jacket for heating or coolingwas equipped with a mechanical stirrer, reflux condenser, thermocoupleand nitrogen inlet tube. The vessel was charged with 343.7 partsdeionized water and 63.8 parts of 49% aqueous solution of polyamine(condensation product of dimethylamine and epichlorohydrin with lowamount multiamine), weight average molecular weight about 344,000. Aftercompletion of dissolution, 93.47 parts of a 52.8% aqueous solution ofacrylamide and 174 parts of an 79.2% aqueous solution of DEAEA.DMS wereadded and mixed. To this mixture, 130.2 parts ammonium sulfate, 10.25parts citric acid, 7.6 parts glycerol, and 13.1 parts of 2% EDTA wereadded and mixed. The pH of the mixture was about 3.2. The vessel wassealed and sparged with nitrogen for about 30 minutes, and thenpolymerization was started by adding 3.93 parts of 2% V-50 at about 48°C. The reaction mixture was held at this temperature for 5 hours. Theoverall conversion was greater than 99%. A stable fluid aqueousdispersion was obtained. The bulk viscosity of this dispersion was about1020 cps as measured with a Brookfield viscometer No. 4 spindle, 30 rpmat 25° C. showing preferable fluidity. The dispersion was dissolved togive a SV of 3.57 cps.

EXAMPLE 39

[0100] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 63.18parts deionized water and 30.8 parts of 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 230,600. Aftercompletion of dissolution, 27.96 parts of a 53.33% aqueous solution ofacrylamide (AMD), 26.02 parts of a 80% aqueous solution of DEAEA.DMS and16.94 parts of a 80% aqueous solution of the methyl chloride quaternarysalt of dimethylaminoethylacrylate (DMAEA.MeCl) were added and mixed. Tothis mixture, 40.7 parts ammonium sulfate, 2.57 parts citric acid, and6.9 parts of 1% EDTA were added and mixed. The pH of the mixture wasabout 3.3. The vessel was sealed and sparged with nitrogen for 30minutes, and then polymerization was started by adding 4.93 parts of 1%V-50. The reaction mixture was raised to 40° C. for 2 hours, and thenraised to and held at 50° C. for 4 hours. The overall conversion wasgreater than 99%. A stable fluid aqueous dispersion was obtained. Thebulk viscosity of this dispersion was about 3840 cps as measured with aBrookfield Viscometer, No. 4 spindle, 30 rpm at 25° C. showing goodfluidity. The dispersion was dissolved to give a SV of 2.14 cps.

EXAMPLE 39A

[0101] A suitable vessel with an external jacket for heating or coolingwas equipped with a mechanical stirrer, reflux condenser, thermocoupleand nitrogen inlet tube. The vessel was charged with 88.37 partsdeionized water and 22.1 parts of 49% aqueous solution of polyamine(condensation product of dimethylamine and epichlorohydrin with lowamount multiamine), weight average molecular weight about 344,000. Aftercompletion of dissolution, 30.9 parts of a 53% aqueous solution ofacrylamide and 18.62 parts of an 79.2% aqueous solution of DEAEA.DMS and28.9 parts of an 80% aqueous solution of DMAEA.MeCl were added andmixed. To this mixture, 47.5 parts ammonium sulfate, 3.05 parts citricacid, 2.2 parts glycerol, and 3.8 parts of 0.5% EDTA were added andmixed. The pH of the mixture was about 3.2. The vessel was sealed andsparged with nitrogen for 30 minutes, and then polymerization wasstarted by adding 4.55 parts of 2% V-50 at about 48° C. The reactionmixture was held at this temperature for 5 hours. The overall conversionwas greater than 99%. A stable fluid aqueous dispersion was obtained.The bulk viscosity of this dispersion was about 2560 cps as measuredwith a Brookfield viscometer No. 4 spindle, 30 rpm at 25° C. showingpreferable fluidity. The dispersion was dissolved to give a SV of 3.44cps.

EXAMPLES 40-42

[0102] Polymerizations were carried out in the same manner as Example 39except that the bulk viscosity was adjusted by varying the level ofammonium sulfate salt as shown in Table 3. These Examples demonstratethat aqueous dispersions having low bulk viscosities and high polymersolids may be prepared, wherein the first cationic polymer is aDMAEA.MeCl/DEAEA.DMS/AMD terpolymer. TABLE 3 FIRST SECOND POLY- POLY-EX- MER MER AMPLE % TOTAL % % % SV NO. SOLIDS SOLIDS SOLIDS SALT BV(cps) (cps) 39 28 22.4 5.6 18.5 2,620 2.99 40 28 22.4 5.6 18 4,310 2.9641 28 22.4 5.6 19 1,820 2.65 42 28 22.4 5.6 19.5 2,000 2.62

EXAMPLE 43

[0103] A suitable vessel equipped with an external jacket for heating orcooling, a mechanical stirrer, reflux condenser, thermocouple andnitrogen inlet tube was charged with 260.35 parts deionized water and117.6 parts of a 40% aqueous solution of poly(DMAEM.MeCl), weightaverage molecular weight about 210,000. After completion of dissolution,107.89 parts of a 52.77% aqueous solution of acrylamide, 99.35 parts ofa 80% aqueous solution of DEAEA.DMS and 64.68 parts of a 80% aqueoussolution of DMAEA.MeCl were added and mixed. To this mixture, 271.92parts ammonium sulfate, 9.83 parts citric acid, and 13.17 parts of 2%EDTA were added and mixed. The pH of the mixture was about 3.3. Thevessel was sealed and sparged with nitrogen for 30 minutes, and thenpolymerization was started by adding 7.53 parts of 2.5% V-50. Thereaction mixture was raised to 40° C. for 2 hours, and then raised toand held at 50° C. for 4 hours. The overall conversion was greater than99%. A stable fluid aqueous dispersion was obtained. The bulk viscosityof this dispersion was about 1240 cps as measured with a BrookfieldViscometer, No. 4 spindle, 30 rpm at 25° C. showing good fluidity. Thedispersion was dissolved to give a SV of 2.74 cps.

EXAMPLE 44

[0104] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and nitrogen inlet tube was charged with 18.86 partsdeionized water and 9 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 200,000. Aftercompletion of dissolution, 4.39 parts of a 53.64% aqueous solution ofacrylamide and 15.19 parts of a 79.3% aqueous solution of DEAEA.DMS wereadded and mixed. To this mixture, 8.4 parts ammonium sulfate, 0.7 partscitric acid, and 2.02 parts of 1% EDTA were added and mixed. The pH ofthe mixture was about 3.3. The vessel was sealed and sparged withnitrogen for 30 minutes, and then polymerization was started by adding1.44 parts of 1% V-50. The reaction mixture was raised to 40° C. for 2hours and then raised to and held at 50° C. for 8 hours. The conversionwas greater than 99%. A stable fluid aqueous dispersion was obtained.The bulk viscosity of this dispersion was about 850 cps as measured witha Brookfield Viscometer, No. 4 spindle, 30 rpm at 25° C. showingpreferable fluidity. The dispersion was dissolved to give a SV of 2.27cps.

EXAMPLES 45-49

[0105] Additional aqueous dispersions were prepared in the same manneras Example 44, demonstrating the effect of ratio of first cationic tosecond cationic polymer and salt content on the bulk viscosity of thedispersion as shown in Table 4. TABLE 4 FIRST SECOND POLY- POLY- EX- MERMER AMPLE % TOTAL % % % SV NO. SOLIDS SOLIDS SOLIDS SALT BV (cps) (cps)44 30 24 6 14  852 2.27 45 30 24 6 12 2,400 2.19 46 30 24 6 13 1,1002.34 47 30 24 6 15 1,770 2.35 48 30 25 5 13 1,260 2.45 49 30 25 5 144,750 2.4 50 30 24  6* 14  780 2.2

EXAMPLE 51

[0106] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and nitrogen inlet tube was charged with 92.9 parts deionizedwater and 30.1 parts of a 41% aqueous solution of poly(DMAEM.MeCl),weight average molecular weight about 395,000. After completion ofdissolution, 15.03 parts of a 53.57% aqueous solution of acrylamide and51.53 part of an 80% aqueous solution of DEAEA.DMS were added and mixed.To this mixture 22 parts of sodium sulfate, 2.57 parts citric acid, and3.45 parts of 2% EDTA were added and mixed. The pH of the mixture wasabout 3.3. The vessel was sealed and sparged with nitrogen for 30minutes, and then polymerization was started by adding 2.46 parts of 2%V-50. The reaction mixture was raised to 40° C. for 2 hours and thenraised to and held at 50° C. for 4 hours. The overall conversion wasgreater than 99%. A stable fluid aqueous dispersion was obtained. Thebulk viscosity of this dispersion was about 1100 cps as measured with aBrookfield Viscometer, No. 4 spindle, 30 rpm at 25° C. The dispersionwas dissolved to give a SV of 2.19 cps. This Example demonstrates theeffectiveness of sodium sulfate.

EXAMPLE 52

[0107] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 17.57parts deionized water and 9 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 200,000. Aftercompletion of dissolution, 4.77 parts of a 53.64% aqueous solution ofacrylamide, 12 parts of a 79.3% aqueous solution of DEAEA.DMS and 2.91parts of an 80% aqueous solution of DMAEA.MeCl were added and mixed. Tothis mixture, 9.6 parts ammonium sulfate, 0.7 parts citric acid, and2.02 parts of 1% EDTA were added and mixed. The pH of the mixture wasabout 3.3. The vessel was sealed and sparged with nitrogen for 30minutes, and then polymerization was started by adding 1.44 parts of 1%V-50. The reaction mixture was raised to 40° C. for 2 hours and thenraised to and held at 50° C. for 4 hours. The overall conversion wasgreater than 99%. A stable fluid aqueous dispersion was obtained. Thebulk viscosity of this dispersion was about 800 cps as measured with aBrookfield Viscometer, No. 4 spindle, 30 rpm at 25° C. showing goodfluidity. The dispersion was dissolved to give a SV of 2.3 cps.

EXAMPLES 53-80

[0108] Polymerizations were carried out in the same manner as Example52. The effect of total polymer solids, first cationic polymercomposition (in terms of % AMD, % DEAEA.DMS and % DMAEA.MeCl in monomerfeed), ratio of first cationic to second cationic polymer, and ammoniumsulfate salt content on the bulk viscosity of the aqueous dispersion isdemonstrated as shown in Table 5. TABLE 5 FIRST SECOND % % % % TOTALPOLYMER POLYMER % SV NO. AMD DEAEA.DMS DMAEA.MeCl SOLIDS % SOLIDS %SOLIDS SALT BV (cps) (cps) 52 45 40 15 30 24 6 16    802 2.3 53 45 40 1530 24 6 12 200,000+ 2.4 54 45 40 15 30 24 6 13  30,900 2.35 55 45 40 1530 24 6 14  4,410 2.35 56 45 40 15 30 24 6 15  1,080 2.42 57 45 40 15 3024 6 17  1,820 2.32 58 45 40 15 30 24 6 18  15,800 2.2 59 45 40 15 30 246 19 200,000+ 60 45 40 15 30 25 5 15  1,940 2.45 61 45 40 15 30 25 5 16 1,260 2.49 62 45 40 15 30 25 5 17  6,010 2.4 63 45 35 20 30 24 6 15 3,120 2.19 64 45 35 20 30 24 6 16  1,340 2.24 65 45 35 20 30 24 6 17 1,140 2.32 66 45 30 25 30 24 6 16 170,000 1.82 67 45 30 25 30 24 6 17 1,890 2.44 68 45 30 25 30 24 6 18  1,400 2.35 69 45 20 35 29.3 23.445.86 18 200,000+ 70 45 20 35 29.3 23.44 5.86 18.5  2,900 2.4 71 45 20 3529.3 23.44 5.86 19  6,600 2.24 72 45 10 45 28.5 22.8 5.7 18 200,000+2.35 73 45 10 45 28.5 22.8 5.7 19 200,000+ 2.34 74 45 10 45 28 22.4 5.619.6 200,000+ 2.5 75 45 20 35 29 23.2 5.8 18 200,000+ 2.2 76 45 20 35 2923.2 5.8 18.5  5,540 2.27 77 45 20 35 29 23.2 5.8 19  3,570 2.47 78 4520 35 28.5 23.2 5.8 18  6,350 2.35 79 45 20 35 28.5 23.2 5.8 18.5  3,0602.4 80 45 20 35 28.5 23.2 5.8 19 200,000+ 2.39

EXAMPLE 81

[0109] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 89parts deionized water and 20.9 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 190,000. Aftercompletion of dissolution, 30.96 parts of a 52.77% aqueous solution ofacrylamide and 21.38 parts of a 80% aqueous solution of DEAEA.DMS wereadded and mixed. To this mixture, 49.5 parts ammonium sulfate, 2.57parts citric acid, and 2.34 parts of 1% EDTA were added and mixed. ThepH of the mixture was about 3.3. The vessel was sealed and sparged withnitrogen for 30 minutes, and then polymerization was started by adding3.34 parts of 1% V-50. The reaction mixture was raised to 40° C. for 2hours and then raised to and held at 50° C. for 4 hours. The combinedconversion was greater than 99%. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of this dispersion was about 280 cps asmeasured with a Brookfield Viscometer, No. 4 spindle, 30 rpm at 25° C.showing good fluidity. The dispersion was dissolved to give a SV of 1.60cps.

EXAMPLES 82-97

[0110] Polymerizations were carried out in the same manner as Example81. The effect of chelant (EDTA) concentration, chain transfer agent(lactic acid), first cationic polymer composition (in terms of % AMD, %DEAEA.DMS, and % DMAEA.MeCl in monomer feed), ratio of first cationic tosecond cationic polymer, and ammonium sulfate salt content on standardviscosity and bulk viscosity are demonstrated as shown in Table 6. TABLE6 % FIRST SECOND % % % % TOTAL POLYMER POLYMER LACTIC EDTA % BV SV NOAMD DEAEA.DMS DMAEA.MeCl SOLIDS % SOLIDS % SOLIDS ACID (ppm) SALT (cps)(cps) 81 80 20 19 15.2 3.8 0 1400 22.5    280 1.6 82 80 20 20 16 4 01400 20 142,000 1.82 83 80 20 20 16 4 0 1400 22.5    840 1.6 84 80 20 1915.2 3.8 0.25 1400 22.5    200 2.05 85 80 20 19 15.2 3.8 0.5 1400 22.5   100 1.67 86 80 20 19 15.2 3.8 0.75 1400 22.5    200 1.87 87 80 20 1915.2 3.8 0 2000 22.5    280 1.61 88 80 20 19 15.2 3.8 0 3000 22.5  4,8001.81 89 80 20 19 15.2 3.8 0.25 2000 22.5    270 1.99 90 80 20 19 15.23.8 0.5 2000 22.5  2,000 2.47 91 80 20 19 15.2 3.8* 0.5 2000 22.5    1402.1 92 80 20 19 15.2 3.8 0.5 2000 22.5    640 2.45 93 80 20 19 15.2 3.80.65 2000 22.5    360 2.4 94 80 20 19 15.2 3.8 0.75 2000 22.5    2252.35 95 80 10 10 19 15.2 3.8 0 1400 22.5    760 2.09 96 80 10 10 19 15.23.8 0.25 1400 22.5    460 2.86 97 80 10 10 19 15.2 3.8 0.5 1400 22.5   340 2.74

EXAMPLE 98

[0111] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 87.97parts deionized water and 20.9 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 190,000. Aftercompletion of dissolution, 33.99 parts of a 52.77% aqueous solution ofacrylamide, 11.74 parts of a 80% aqueous solution of DEAEA.DMS and 7.64parts of a 80% aqueous solution of DMAEA.MeCl were added and mixed. Tothis mixture, 49.5 parts ammonium sulfate, 2.57 parts citric acid, and2.34 g of 2% EDTA were added and mixed. The pH of the mixture was about3.3. The vessel was sealed and sparged with nitrogen for 30 minutes, andthen polymerization was started by adding 2.34 parts of 1% V-50. Thereaction mixture was raised to 40° C. for 2 hours and then raised to andheld at 50° C. for 4 hours. The overall conversion was greater than 99%.A stable fluid aqueous dispersion was obtained. The bulk discosity ofthis dispersion was about 760 cps as measured with a BrookfieldViscometer, No. 4 spindle, 30 rpm at 25° C. The dispersion was dissolvedto give a SV of 2.09 cps.

EXAMPLES 99-100

[0112] Polymerizations were carried out in the same manner as Example97. The effect of chain transfer agent (lactic acid) concentration onbulk viscosity is demonstrated as shown in Table 7. TABLE 7 FIRST SECONDLACTIC EXAMPLE % TOTAL POLYMER POLYMER ACID % BV SV NO. SOLIDS % SOLIDS% SOLIDS % SALT (cps) (cps) 98 19 15.2 3.8 0 22.5 760 2.09 99 19 15.23.8 0.25 22.5 460 2.86 100  19 15.2 3.8 0.5 22.5 340 2.74

EXAMPLE 101

[0113] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, thermocouple and nitrogen inlet tube was charged with 82.15parts deionized water and 30.8 parts of a 20% aqueous solution ofpoly(diallyldimethylammonium chloride) (poly(DADMAC)), weight averagemolecular weight about 289,000. After completion of dissolution, 48.24parts of a 52.77% aqueous solution of acrylamide and 13.27 parts of an80% aqueous solution of DEAEA.DMS were added and mixed. To this mixture,49.5 parts ammonium sulfate, 2.57 parts citric acid, 1.67 parts of 10%lactic acid, and 3.34 parts of 2% EDTA were added and mixed. The pH ofthe mixture was about 3.3. The vessel was sealed and sparged withnitrogen for 30 minutes, and then polymerization was started by adding3.34 parts of 1% V-50. The reaction mixture was raised to 40° C. for 2hours and then raised to and held at 50° C. for 4 hours. The combinedconversion was greater than 99%. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of this dispersion was about 960 cps asmeasured with a Brookfield Viscometer, No. 4 spindle, 30 rpm at 25° C.showing preferable fluidity. The dispersion was dissolved to give a SVof 3.67 cps. This Example demonstrates aqueous dispersions havingpoly(DADMAC) as the second cationic polymer.

EXAMPLE 101A

[0114] A suitable vessel with an external jacket for heating or coolingwas equipped with a mechanical stirrer, reflux condenser, thermocoupleand nitrogen inlet tube. The vessel was charged with 381.3 partsdeionized water and 30.9 parts of 49% aqueous solution of polyamine(condensation product of dimethylamine and epichlorohydrin with lowamount multiamine), weight average molecular weight about 344,000. Aftercompletion of dissolution, 156.3 parts of a 52.08% aqueous solution ofacrylamide and 47.83 parts of an 79.2% aqueous solution of DEAEA.DMSwere added and mixed. To this mixture, 193.2 parts ammonium sulfate,10.25 parts citric acid, 7.16 parts glycerol, and 11.93 parts of 2% EDTAwere added and mixed. The pH of the mixture was about 3.2. The vesselwas sealed and sparged with nitrogen for 30 minutes, and thenpolymerization was started by adding 1.19 parts of 2% V-50 at about 48°C. The reaction mixture was held at this temperature for 5 hours. Theoverall conversion was greater than 99%. A stable fluid aqueousdispersion was obtained. The bulk viscosity of this dispersion was about640 cps as measured with a Brookfield viscometer No. 4 spindle, 30 rpmat 25° C. showing preferable fluidity. The dispersion was dissolved togive a SV of 4.5 cps. This Example demonstrates aqueous dispersionshaving polyamine as the second polymer.

EXAMPLE 102

[0115] A suitable vessel equipped with an external jacket for heating orcooling, mechanical stirrer, reflux condenser, thermocouple and nitrogeninlet tube was charged with 262.6 parts deionized water, 47.4 parts of a40% aqueous solution of poly(DMAEM.MeCl), weight average molecularweight about 41,500, and 92.60 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 205,000. Aftercompletion of dissolution, 88.1 parts of a 53.12% aqueous solution ofacrylamide and 133.9 parts of a 72.6% aqueous solution of the methylchloride quaternary salt of diethylaminoethylacrylate (DEAEA.MeCl) wereadded and mixed. To this mixture, 144 parts ammonium sulfate, 2.644parts citric acid, and 14.4 parts of 1% EDTA were added and mixed. ThepH of the mixture was about 3.3. The vessel was sealed and sparged withnitrogen for 30 minutes, and then polymerization was started by adding14.4 parts of 2% V-50. The reaction mixture was raised to and held at40-45° C. for 6 hours. The conversion was greater than 99.9%. A stablefluid aqueous dispersion was obtained. The bulk viscosity of thisdispersion was about 2,200 cps as measured with a Brookfield Viscometer,No. 4 spindle, 30 rpm at 25° C. The dispersion was dissolved to give aSV of 3.31 cps. This Example demonstrates an aqueous dispersion having athird cationic polymer.

EXAMPLE 103

[0116] Polymerization was carried out in the same manner as Example 102,except that the two poly(DMAEM.MeCl) polymers were replaced with asingle poly(DMAEM.MeCl) having a weight average molecular weight ofabout 1,500,000. The bulk viscosity of this dispersion was about 8,000cps as measured with a Brookfield Viscometer, No. 4 spindle, 30 rpm at25° C. showing preferable fluidity. The dispersion was dissolved to givea SV of 2.45 cps.

EXAMPLE 104

[0117] A suitable vessel equipped with an external jacket for heating,mechanical stirrer, reflux condenser, thermocouple and nitrogen inlettube was charged with 23.8 parts deionized water and 25.3 parts of a 20%aqueous solution of poly(DADMAC), weight average molecular weight about289,000. After completion of dissolution, 7.9 parts of a 53.1% aqueoussolution of acrylamide and 11.3 parts of a 77.9% aqueous solution ofDEAEA.MeCl were added and mixed. To this mixture, 18 parts ammoniumsulfate, 1.08 parts citric acid, 0.37 part of 5% EDTA, and 0.9 partglycerol were added and mixed. The pH of the mixture was about 3.3. Thevessel was sealed and sparged with nitrogen for 30 minutes, and thenpolymerization was started by adding 1.3 parts of 1% V-50 at 40° C. Thistemperature was held for 2 hours and then was raised to 50° C. andmaintained at this temperature for 8 hours. The residual acrylamidelevel was about 209 parts per million (ppm). A stable fluid aqueousdispersion was obtained. The bulk viscosity of this dispersion was about2,950 cps as measured with a Brookfield Viscometer, No. 4 spindle, 30rpm at 25° C. showing preferable fluidity. The dispersion was dissolvedto give a SV of 2.47 cps.

EXAMPLES 105-108

[0118] Polymerizations were carried out in the same manner as Example104, except that part of the poly(DADMAC) was replaced with apoly(DADMAC) polymer having a lower weight average molecular weight. Theeffect on the aqueous dispersion bulk viscosity of including the thirdpolymer is shown in Table 8. TABLE 8 % FIRST SECOND SECOND THIRD THIRDTOTAL POLYMER POLYMER POLYMER POLYMER POLYMER % BV SV NO. SOLIDS %SOLIDS % SOLIDS MW % SOLIDS MW SALT (cps) (cps) 104 21.2 14.5 5.06289,000 20 2,950 2.47 105 21.2 14.5 3.73 289,000 1.89 10,100 20 2,2002.4 106 21.2 14.5 3.73 289,000 1.89 53,400 20 1,950 2.4 107 21.2 14.53.73 289,000 1.89 67,900 20 2,020 2.39 108 21.2 14.5 3.73 289,000 1.89100,000  20 1,990 2.42

EXAMPLE 109

[0119] An aqueous dispersion containing 12.5% ammonium sulfate andhaving a polymer solids of 30%, a bulk viscosity of about 7200 cps and astandard viscosity of about 2.34 cps was prepared in the same manner asin Example 2.

EXAMPLE 110

[0120] An aqueous dispersion containing 15.5% ammonium sulfate andhaving a polymer solids level of 28%, a bulk viscosity of about 2640 cpsand a standard viscosity of about 2.4 cps was prepared in the samemanner as in Example 9.

EXAMPLES 111-133

[0121] Various amounts of either ammonium sulfate, sodium thiocyanate,or 1,3-benzenedisulfonate (1,3-BDS) were added to the base aqueousdispersions of Example 109, Example 110, Example 103, Example 1, Example102 and Example 142. The bulk viscosities of the resultant aqueousdispersions were further reduced as shown in Table 9. These Examplesdemonstrate that the bulk viscosity of aqueous dispersions may bereduced by adding salt to the dispersion, and that the addition of1,3-BDS may be more effective than ammonium sulfate on a weight basis.Substantially similar results are obtained by polymerizing the monomersin the presence of the salts. TABLE 9 BV of Ex- Base Base % ampleAqueous Aqueous Added Total % Total BV No. Dispersion Dispersion SaltSalt Solids (cps) 111 Example 109 7200 (NH₄)₂SO₄ 14.21 29.41 2100 112Example 109 7200 (NH₄)₂SO₄ 15.86 28.84 1,000 113 Example 109 7200(NH₄)₂SO₄ 17.45 28.3 501 114 Example 109 7200 (NH₄)₂SO₄ 19 27.8 319 115Example 109 7200 1,3-BDS 13.37 29.7 2200 116 Example 109 7200 1,3-BDS14.21 29.41 1160 117C Example 109 7200 1,3-BDS 15 29.12 FL 118 Example110 2640 NaSCN 16.3 27.7 540 119C Example 110 2640 NaSCN 17.15 27.45 FL120C Example 110 2640 NaSCN 17.96 27.18 FL 121 Example 103 8000 1,3-BDS19.6 24.51 1660 122 Example 103 8000 1,3-BDS 21.15 24.04 762 123 Example103 8000 1,3-BDS 22.64 23.58 FL 124 Example 103 8000 (NH₄)₂SO₄ 19.624.51 3440 125 Example 103 8000 (NH₄)₂SO₄ 21.15 24.04 1990 126 Example103 8000 (NH₄)₂SO₄ 22.64 23.58 1300 127 Example 103 8000 (NH₄)₂SO₄ 24.0723.15 982 128 Example 1 2300 (NH₄)₂SO₄ 19 27.8 501 129 Example 102 2200(NH₄)₂SO₄ 19.6 24.51 1002 130 Example 102 2200 (NH₄)₂SO₄ 21.15 14.04 441131 Example 102 2200 (NH₄)₂SO₄ 22.64 23.58 301 132 Example 102 2200(NH₄)₂SO₄ 24.07 23.15 200 133 Example 142 10,000 (NH₄)₂SO₄ 24.07 23.151380

EXAMPLE 134

[0122] About 18 parts of the aqueous dispersion of Example 49 and about20 part of the aqueous dispersion of Example 91 were intermixed withstirring. The resultant aqueous dispersion blend was stable and veryuniform with a bulk viscosity of about 880 cps, demonstrating thatdifferently charged dispersions may be blended to prepare an aqueousdispersion having an intermediate charge. The aqueous dispersion blendhad an overall charge of about 40% and a SV of 2.5 cps.

EXAMPLE 135

[0123] About 18 parts of a high charge aqueous dispersion prepared as inExample 48 and about 18 parts of a low charge aqueous dispersionprepared as in Example 101 were intermixed with stirring. The resultantaqueous dispersion blend was stable and very uniform with a bulkviscosity of about 2300 cps, demonstrating that differently chargeddispersions may be blended to prepare an aqueous dispersion having anintermediate charge. The resultant aqueous dispersion contained fourdifferent polymers.

EXAMPLE 136 (COMPARATIVE)

[0124] A polymerization was conducted in the same manner as Example 9,except that the DEAEA.DMS was replaced with an equal weight ofDMAEA.MeCl. During the process of polymerization, the contents of thevessel became so viscous that stirring became impossible. The productwas obtained as a gel without fluidity. This Example demonstrates thatreplacement of DMAEA.MeCl with DEAEA.DMS results in an aqueousdispersion having a dramatically lower bulk viscosity.

EXAMPLE 137 (COMPARATIVE)

[0125] A polymerization was conducted in the same manner as Example 50,except that the DEAEA.DMS was replaced with an equal weight ofDMAEA.MeCl. During the process of polymerization, the contents of thevessel became so viscous that stirring became impossible. The productwas obtained as a gel without fluidity. This Example demonstrates thatreplacement of DMAEA.MeCl with DEAEA.DMS results in an aqueousdispersion having a dramatically lower bulk viscosity.

EXAMPLE 138 (COMPARATIVE)

[0126] A polymerization was conducted in the same manner as Example 91,except that the DEAEA.DMS was replaced with an equal weight ofDMAEA.MeCl. During the process of polymerization, the contents of thevessel became so viscous that stirring became impossible. The productwas obtained as a gel without fluidity. This Example demonstrates thatreplacement of DMAEA.MeCl with DEAEA.DMS results in an aqueousdispersion having a dramatically lower bulk viscosity.

EXAMPLE 139 (COMPARATIVE)

[0127] A polymerization was conducted in the same manner as Example 100,except that the DEAEA.DMS was replaced with an equal weight ofDMAEA.MeCl. During the process of polymerization, the contents of thevessel became so viscous that stirring became impossible. The productwas obtained as a gel without fluidity. This Example demonstrates thatreplacement of DMAEA.MeCl with DEAEA.DMS results in an aqueousdispersion having a dramatically lower bulk viscosity.

EXAMPLE 140

[0128] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and nitrogen inlet tube was charged with 20 parts deionizedwater and 10.51 parts of a 40% aqueous solution of poly(DMAEM.MeCl),weight average molecular weight about 210,000. After completion ofdissolution, 6.57 parts of a 53.27% aqueous solution of acrylamide,14.56 parts of an 80% aqueous solution of DMAEA.MeCl and 4.15 parts of a80% aqueous solution of DMAEA.BzCl were added and mixed. To thismixture, 10.8 parts ammonium sulfate, 0.4 parts citric acid, and 1.51parts of 1% EDTA were added and mixed. The pH of the mixture was about3.3. The vessel was sealed and sparged with nitrogen for 30 minutes, andthen polymerization was started by adding 1.08 parts of 1% V-50. Thereaction mixture was raised to 40° C. 2 hours by placing the vessel in awater bath and then raised to 50° C. for 6 hours. The conversion wasgreater than 99%. A stable fluid aqueous dispersion was obtained. Thebulk viscosity of this dispersion was about 2000 cps showing preferablefluidity as measured with a Brookfield Viscometer No. 4 spindle, 30 rpmat 25° C. The dispersion was dissolved to give a SV of 2.2 cps.

EXAMPLES 141-144

[0129] Polymerizations were carried out in the same manner as Example140. The effect of the composition of the first polymer (given in termsof % AMD, % DMAEA.MeCl, and DMAEA.BzCl in monomer feed) and molecularweight of the poly(DMAEM.MeCl) on the aqueous dispersion bulk viscosityis shown in Table 10. TABLE 10 FIRST SECOND SECOND % % % % TOTAL POLYMERPOLYMER POLYMER % BV SV NO. AMD DMAEA.MeCl DMAEA.BzCl SOLIDS % SOLIDS %SOLIDS MW SALT (cps) (cps) 140 60 25 15 25 18 7   210,000 18  2,000 2.2141 60 25 15 25 18 7   500,000 18 13,200 2.34 142 60 25 15 25 18 71,500,000 18 10,000 2.4 143 60 25 15 25 18 7   800,000 18 11,500 2.2 14460 29.2 10.8 25 19 6   200,000 18  8,680 2.59

EXAMPLES 145-150 (COMPARATIVE)

[0130] Polymerizations were carried out in the same manner as Example140 at different ratios of AMD/DMAEA.MeCI/DMAEA.BzCI/DEAEA.DMS exceptthat the poly(DMAEM.MeCl) was omitted. During the polymerizationprocess, the contents of the vessel became very viscous to the pointthat stirring became impossible. The resulting polymerization productwas obtained as a clear gel, a homogeneous composition without fluidityas shown in Table 11. TABLE 11 % % % % % NO. AMD DMAEA.MeCl DMAEA.BzClDEAEA.DMS SOLIDS SALT BV (cps) 145C 50 40 10 14.4 20 Gel 146C 45 40 1514.4 20 Gel 147C 60 29.2 10.8 18 18 Gel 148C 60 25 15 18 18 Gel 149C 555 40 18 18 Gel 150C 55 5 40 25 18 Gel

EXAMPLES 151-153

[0131] An aqueous dispersion having a bulk viscosity of about 3570 cpswas prepared in the same manner as Example 13. The dispersion wasconcentrated by placing about 135 parts into a suitable vessel andheating to 45° C. under flowing nitrogen. A total of 26 parts of waterwas removed in two stages by this dehydration process. The aqueousdispersion remained stable demonstrating that dehydration is effectivefor achieving high solids, low bulk viscosity aqueous dispersions asshown in Table 12. TABLE 12 Polymer Bulk Example No. Solids (%)Viscosity (cps) 151 (as polymerized) 28.0 3570 152 31.5 660 153 34.63260

EXAMPLE 154

[0132] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and a nitrogen inlet tube was charged with 277.75 partsdeionized water and 112.0 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 200,000. Aftercompletion of dissolution, 89.03 parts of a 53.64% aqueous solution ofacrylamide, and 164.93 parts of an 80% solution of DEAEA.DMS were addedand mixed. To this mixture, 124.0 parts ammonium sulfate, 9.36 partscitric acid, and 5.02 parts of a 1% solution of EDTA were added andmixed. The pH of the mixture was about 3.3. The contents were heated to48° C. and sparged with nitrogen for 30 minutes, and then polymerizationwas started by adding 17.92 parts of 1% aqueous solution of V-50. Thereaction mixture was maintained at 48° C. for 5 hours. About 3.5 hoursinto the polymerization the aqueous dispersion bulk viscosity began tonoticeably increase. The final bulk viscosity of the aqueous dispersionwas about 8,000 cps as measured with a Brookfield Viscometer No. 4spindle, 30 rpm at 25° C.

EXAMPLE 155-156

[0133] Duplicate polymerizations ware carried out in a similar manner toExample 154 except that an additional amount of ammonium sulfate (4% ontotal) was added approximately 3 hours after initiation ofpolymerization. This prevented any substantial increase in bulkviscosity during the polymerization and resulted in a final bulkviscosity that was lower than the bulk viscosity obtained in Example 154as shown in Table 13. TABLE 13 Example No. Final Bulk Viscosity (#4spindle, 30 rpm) 155 300 cps 156 500 cps

EXAMPLES 157-172

[0134] General Polymerization Procedure: The following components weremixed together in a suitable vessel and the pH was adjusted to about 3.5with a 28 wt. % solution of ammonium hydroxide. Acrylamide (55.5 wt. %) 5.34 parts DEAEA.DMS (80 wt. %) 10.35 parts Citric acid  0.58 partsAmmonium sulfate  7.78 parts poly(DMAEM.MeCl) (40 wt. %, 200,000 MW) 7.03 parts Deionized Water 16.22 parts V-50 (1 wt. %)  1.12 parts EDTA(1 wt. %)  1.57 parts Methylenebisacrylamide (MBA) variable Lactic acid(chain transfer agent) variable

[0135] Forty parts of the solution were placed into a suitable vesseland the solution was sparged with nitrogen. The vessel was sealed andplaced into a 40° C. water bath for 2 hours. The temperature was thenincreased to 50° C. and maintained for an additional 3 hours. Resultsare summarized in Table 14, showing that substantial levels of branchingagent and chain transfer agent can be incorporated into aqueousdispersions of water-soluble and water-swellable polymers. The aqueousviscosity values were obtained by dissolving or dispersing the aqueousdispersions in the same general manner as for the standard viscosityvalues described above, except that the polymer concentration was 0.135wt. %. TABLE 14 Dispersion bulk Ex. Lactic acid (wt. MBA (ppm onviscosity (#4 Aqueous No. % on monomer) monomer) spindle, 30 rpm)Viscosity 157 0 0 — 3.91 158 0.4 0 — 3.41 159 0.8 0 — 3.04 160 0 0 11003.71 161 0 2 1000 3.61 162 0 4 1600 3.66 163 0 6 2500 3.31 164 0 0 22003.11 165 0 10 3300 1.90 166 0 15 3300 1.77 167 0 20 8100 1.67 168 0 01200 2.81 169 0 30 1800 1.46 170 0 40 3500 1.43 171 0 50 — 1.44 172 0100 — 1.28

EXAMPLE 173

[0136] A aqueous dispersion was prepared as in Example 155. The aqueousdispersion had a bulk viscosity of about 240 cps and an aqueousviscosity (obtained as in Examples 157-172) of 3.55 cps.

EXAMPLE 174

[0137] The aqueous dispersion of Example 173 was spray-dried on acommercially available laboratory spray dryer. The chamber of thelaboratory spray dryer was 760 millimeters (mm) in diameter with a 860mm vertical side and a 65 degree conical bottom. Nominal gas flowthrough the dryer was about 180 cubic meters per hour. The aqueousdispersion feed was fed at the center of the top of the chamber using avariable speed pump, through a two-fluid nozzle using air foratomization. The outlet gas temperature was 86° C. and controlled byvarying the inlet gas temperature (169° C.) and the feed rate (60milliliters/minute). To provide an inert atmosphere, the spray-dryer wassupplied with nitrogen gas from a cryogenic storage tank. The driedpolymer product was discharged through the bottom of the dryer cone to acyclone where the dry product was removed and collected. Residence timein the dryer was about 14 seconds. The resultant spray-dried polymerparticles, which had a volatiles content of 3.4% and a bulk density ofabout 0.50 grams per cubic centimeter (g/cc), were readily soluble inwater and had a SV a 3.49 cps.

EXAMPLE 175

[0138] The dissolution rate of the spray-dried polymer of Example 174was compared to a dry polymer of similar composition obtained byspray-drying a commercial water-in-oil emulsion. Solutions were preparedin a wide mouth quart jar using a 2.5 inch magnetic stirring bar. Thestirring rate was adjusted so that a deep vortex was obtained in thewater. The dry polymer was added slowly over a period of 5 minutes atthe edge of the vortex to avoid clumping. The spray-dried polymer ofExample 174 wet more readily and completely dissolved over a period of30-40 minutes, giving a clear solution. In contrast, the dry polymerobtained by spray-drying an inverse emulsion did not wet as rapidly andwas not completely dissolved after two hours. This Example demonstratesthat a dry polymer obtained by spray-drying an aqueous dispersion of theinstant invention dissolved faster than a dry polymer obtained byspray-drying a corresponding water-in-oil emulsion.

EXAMPLE 176C

[0139] The procedure of U.S. Pat. No. 5,403,883 Example 1 was followed.A dispersion having a bulk viscosity of about 10,600 cps (#4 spindle, 30rpm) was obtained.

EXAMPLE 177

[0140] The procedure of U.S. Pat. No. 5,403,883 Example 1 was followed,except that the 2-trimethlyammoniumethyl acrylate chloride was replacedby an equal weight of DEAEA.MeCl. The resulting aqueous dispersion had abulk viscosity of about 6,900 cps (#4 spindle, 30 rpm), demonstratingimproved bulk viscosity as compared to Example 176C.

EXAMPLE 178

[0141] A suitable vessel equipped with a mechanical stirrer, refluxcondenser, and a nitrogen inlet tube was charged with 22.94 partsdeionized water and 10.5 parts of a 40% aqueous solution ofpoly(DMAEM.MeCl), weight average molecular weight about 245,000. Aftercompletion of dissolution, 6.47 parts of a 54.20% aqueous solution ofacrylamide, and 7.49 parts of the propyl chloride quaternary salt ofdimethylaminoethyl acrylate were added and mixed. To this mixture, 10.8parts ammonium sulfate, 0.7 parts citric acid, and 0.76 parts of a 2%solution of EDTA were added and mixed. The pH of the mixture was about3.3. The vessel was sealed and sparged with nitrogen for 30 minutes, andthen polymerization was started by addition of 0.54 g of 2% aqueoussolution of V-50. The reaction mixture was heated to 40° C. for 2 hoursand then raised to 50° C. and held for an additional 4 hours. Theconversion was greater than 99%. A stable fluid aqueous dispersion wasobtained. The bulk viscosity of the aqueous dispersion was about 1300cps showing preferable fluidity as measured with a BrookfieldViscometer, No. 4 spindle, 30 rpm at 25° C. The aqueous dispersion wasdissolved to give a SV of 2.1 cps. This Example demonstrates that,despite Comparative Example 1 of EP 0 525 751 A1, an aqueous dispersionmay be formed when the first polymer contains recurring units of thepropyl chloride quaternary salt of dimethylaminoethylacrylate.

EXAMPLE 179

[0142] An aqueous dispersion was prepared in a similar manner to Example40 except that the first polymer composition wasAMD/DEAEA.DMS/DMAEA.MeCl (60/30/10 mole). The aqueous dispersion had abulk viscosity of about 3,600 cps (No. 4 spindle, 30 rpm at 25° C.) anda SV of 2.64 cps.

EXAMPLE 180

[0143] An aqueous dispersion was prepared in a similar manner to Example40 except that the first polymer composition wasAMD/DEAEA.DMS/DMAEA.MeCl (60/25/15 mole). The aqueous dispersion had abulk viscosity of about 1,000 cps (No. 4 spindle, 30 rpm at 25° C.) anda SV of 2.87 cps.

EXAMPLE 180A-180E

[0144] Polymerizations were carried out in a similar manner to Example39A except that the bulk viscosity was adjusted by utilizing the saltsshown in Table 1. These examples demonstrate that aqueous dispersionshaving low bulk viscosities and high polymer solids may be prepared,where the first cationic polymer is DMAEA.MeCl/DEAEA.DMS/AMD (35/5/60mole) and the second polymer is polyamine, and that the viscosities maybe adjusted with salts. TABLE 14A First Second % % Total Polymer PolymerSalt % Salt BV SV Ex. Solids % Solids % Solids A B (cps) (cps) 180A 2619.25 6.74 22.50 0 80,000 2.86 180B 26 18.57 7.43 22.50 0 10,700 2.70180C 26 18.57 7.43 19.35 3.15 10,200 3.24 180D 26 18.57 7.43 19.35 3.15 3,810 3.06 180E 26 18.57 7.43 19.35 3.15  4,310 2.92

EXAMPLES 181-261

[0145] The performance of aqueous dispersions of the instant inventionwas determined by measuring free drainage rate and cake solids fromdewatered sludge as follows: Two hundred grams of sewage sludge from amunicipal waste treatment plant were weighed into each of a series ofjars. Solutions of the aqueous dispersions and of W/O, a commercialwater-in-oil emulsion control (60/40 mole % AMD/DMAEA.MeCl), wereprepared so that the concentration of the polymer was about 0.2%.Various doses of the polymer solutions were intermixed with the sludgesamples and agitated at 500 rpm for 10 seconds (500 rpm/10 seconds) orat 1000 rpm for 5 seconds (1000 rpm/5 seconds) with an overhead mixer.The resultant aqueous mixture of flocculated sludge was dewatered bypouring it into a Buchner funnel containing a 35 mesh stainless steelscreen; the free drainage was determined by measuring the milliliters offiltrate collected in 10 seconds. Cake solids were determined by dryingthe pressed sludge at 105° C. The results are shown in Table 15, witheach polymer identified by previous Example No., free drainage in unitsof milliliters/10 seconds, mixing in rpm/seconds, dosage in units ofpounds of polymer per ton of dry sludge, and cake solids as a weightpercent of dry solids in wet cake. The notation “N/A” in the Table meansthat an accurate cake solids value could not be obtained. These Examplesshow that the performance of the aqueous dispersions of the instantinvention is substantially equivalent or superior to a comparablecommercial product. TABLE 15 Free Cake No. Polymer Mixing DosageDrainage Solids (%) 181 102  500/10 24.4 137 17.3 182 102  500/10 26.7140 16.9 183 102  500/10 28.9 128 17.1 184 103  500/10 20 138 15.8 185103  500/10 22.2 155 16.5 186 103  500/10 24.4 158 16.5 187 103  500/1026.7 162 15.7 188C W/O  500/10 24.4 112 15.0 189C W/O  500/10 26.7 12215.6 190C W/O  500/10 28.9 114 15.2 191 102 1000/5 20.2 142 15.5 192 1021000/5 22.2 145 15.8 193 102 1000/5 26.7 140 15.3 194 103 1000/5 24.4130 15.7 195 103 1000/5 26.7 138 15.8 196 103 1000/5 28.9 145 15.2 197CW/O 1000/5 22.2 112 16.0 198C W/O 1000/5 24.4 120 16.2 199C W/O 1000/526.7 110 15.7 200  9  500/10 23 144 16.6 201  9  500/10 27.2 160 17.0202  9  500/10 31.4 140 17.1 203 179  500/10 23 144 17.0 204 179  500/1027.2 153 17.6 205 179  500/10 31.4 152 17.4 206 180  500/10 23 100 16.9207 180  500/10 27.2 130 16.8 208 180  500/10 31.4 125 17.1 209C W/O 500/10 23 99 14.9 210C W/O  500/10 27.2 92 15.2 211  9 1000/5 25.1 9617.6 212  9 1000/5 29.3 97 18.0 213  9 1000/5 31.4 93 17.9 214 1791000/5 29.3 107 17.7 215 179 1000/5 31.4 92 18.4 216 179 1000/5 35.6 10418.7 217 180 1000/5 25.1 84 16.9 218 180 1000/5 29.3 92 17.9 219 1801000/5 31.4 136 17.1 220 180 1000/5 35.6 104 17.1 221C W/O 1000/5 25.1110 16.1 222C W/O 1000/5 29.3 112 16.5 223C W/O 1000/5 31.4 108 16.8 224 44  500/10 22.1 140 17.5 225  44  500/10 24.5 138 17.0 226  44  500/1027 139 17.4 227  44 1000/5 22.1 120 19.0 228  44 1000/5 25.8 117 19.3229  44 1000/5 29.4 104 19.5 230C W/O  500/10 18.4 108 NA 231C W/O 500/10 22.1 110 NA 232C W/O  500/10 25.8 66 NA 233C W/O 1000/5 22.1 12817.9 234C W/O 1000/5 25.8 102 17.6 235  61  500/10 16.9 130 17.2 236  61 500/10 18.6 140 18.0 237  61  500/10 21.9 130 17.3 238  67  500/10 15.280 16.8 239  67  500/10 16.9 105 17.8 240  67  500/10 18.6 126 18.2 241CW/O  500/10 15.2 116 16.2 242C W/O  500/10 16.9 116 15.6 243C W/O 500/10 18.8 82 15.4 244 140  500/10 26.5 138 18.0 245 140  500/10 29.4140 18.5 246 140  500/10 32.4 130 18.2 247 140 1000/5 29.2 118 17.8 248140 1000/5 32.4 129 18.4 249 140 1000/5 35.7 137 19.0 250 142  500/1026.5 120 16.9 251 142  500/10 29.4 142 17.2 252 142  500/10 32.4 12717.1 253 142 1000/5 25.9 120 17.3 254 142 1000/5 29.2 140 17.8 255 1421000/5 32.4 138 18.3 256C W/O  500/10 14.7 76 14.0 257C W/O  500/10 17.6114 14.8 258C W/O  500/10 20.6 105 14.8 259C W/O 1000/5 22.7 104 16.8260C W/O 1000/5 25.9 134 16.3 261C W/O 1000/5 29.2 113 16.7

EXAMPLES 262-263

[0146] The performance of the aqueous dispersions of Examples 118 and121 is determined by measuring free drainage rate and cake solids fromdewatered sludge by following the procedure of Examples 181-261. Similarresults are obtained.

EXAMPLE 264

[0147] A solution of the spray-dried polymer of Example 174 is preparedso that the concentration of the polymer is about 0.2%. The performanceis determined by measuring free drainage rate and cake solids fromdewatered sludge by following the procedure of Examples 181-261. Similarresults are obtained.

EXAMPLES 265-277

[0148] Solutions of the aqueous dispersions and spray-dried polymers ofExamples 9, 44, 61, 67, 102, 103, 118, 121, 140, 142, 174, 179, and 180are prepared so that the concentration of the polymer is about 0.2%. Theperformance is determined by measuring free drainage rate by followingthe procedure of Examples 181-261, except that a 1% suspension of papersolids is dewatered instead of sewage sludge. Similar results areobtained.

EXAMPLES 278-293

[0149] Aqueous admixtures are prepared by intermixing the aqueousdispersions of Examples 157-172 with water so that the concentration ofthe polymer is about 0.2%. The performance is determined by measuringfree drainage rate by following the procedure of Examples 181-261,except that a 1% suspension of paper solids is dewatered instead ofsewage sludge. Similar results are obtained.

We claim:
 1. An aqueous dispersion comprising: a first cationic polymer comprising acrylamide recurring units and recurring units of a quaternary salt of a dialkylamino(alk)acrylate, wherein said first cationic polymer is substantially free of hydrophobic recurring units; a second cationic polymer; a first kosmotropic salt; and a second kosmotropic salt; wherein said aqueous dispersion contains a total amount of about 5% or greater, by weight based on total weight, of said first kosmotropic salt and said second kosmotropic salt.
 2. The aqueous dispersion of claim 1 wherein said recurring units of a quaternary salt of a dialkylamino(alk)acrylate are recurring units selected from the group consisting of methyl chloride salt of diethylaminoethylacrylate, dimethyl sulfate salt of diethylaminoethylacrylate, methyl chloride salt of dimethylaminoethylacrylate, and dimethyl sulfate salt of dimethylaminoethylacrylate.
 3. The aqueous dispersion of claim 1 wherein said recurring units of a quaternary salt of a dialkylamino(alk)acrylate are recurring units of methyl chloride quaternary salt of dimethylaminoethylacrylate.
 4. The aqueous dispersion of claim 3 wherein said first kosmotropic salt is selected from the group consisting of ammonium sulfate and sodium sulfate.
 5. The aqueous dispersion of claim 4 wherein said second kosmotropic salt contains an anion selected from the group consisting of acetate, tartrate and citrate.
 6. The aqueous dispersion of claim 4 wherein said first kosmotropic salt and said second kosmotropic salt are each individually present in an amount of about 1% or greater, by weight based on total weight.
 7. The aqueous dispersion of claim 1 further comprising a viscosity-reducing additive selected from the group consisting of glycerin, glycerol, alcohol, and glycol.
 8. The aqueous dispersion of claim 1 having a bulk viscosity of about 2,500 cps or less.
 9. The aqueous dispersion of claim 1 having a standard viscosity of about 2.0 cps or greater.
 10. An aqueous dispersion comprising: a first cationic polymer comprising acrylamide recurring units and recurring units selected from the group consisting of methyl chloride salt of diethylaminoethylacrylate, dimethyl sulfate salt of diethylaminoethylacrylate, methyl chloride salt of dimethylaminoethylacrylate, and dimethyl sulfate salt of dimethylaminoethylacrylate, wherein said first cationic polymer is substantially free of hydrophobic recurring units; a second cationic polymer; a first kosmotropic salt selected from the group consisting of ammonium sulfate and sodium sulfate; and a second kosmotropic salt containing an anion selected from the group consisting of acetate, tartrate and citrate; wherein said aqueous dispersion contains a total amount of about 5% or greater, by weight based on total weight, of said first kosmotropic salt and said second kosmotropic salt.
 11. An aqueous dispersion comprising: a first cationic polymer comprising acrylamide recurring units and recurring units of a quaternary salt of a dialkylamino(alk)acrylate; a second cationic polymer; a first kosmotropic salt selected from the group consisting of ammonium sulfate and sodium sulfate; and a second kosmotropic salt containing an anion selected from the group consisting of acetate, tartrate and citrate; and a viscosity-reducing additive; wherein said aqueous dispersion contains a total amount of about 5% or greater, by weight based on total weight, of said first kosmotropic salt and said second kosmotropic salt; and wherein said aqueous dispersion has a weight average molecular weight of greater than 2,000,000.
 12. The aqueous dispersion of claim 11 wherein said recurring units of a quaternary salt of a dialkylamino(alk)acrylate are recurring units selected from the group consisting of methyl chloride salt of diethylaminoethylacrylate, dimethyl sulfate salt of diethylaminoethylacrylate, methyl chloride salt of dimethylaminoethylacrylate, and dimethyl sulfate salt of dimethylaminoethylacrylate.
 13. The aqueous dispersion of claim 12 wherein said first cationic polymer further comprises recurring units of a benzyl chloride salt of dimethylaminoethylacrylate.
 14. The aqueous dispersion of claim 13 wherein said first kosmotropic salt is ammonium sulfate.
 15. The aqueous dispersion of claim 14 wherein said second kosmotropic salt contains an acetate anion.
 16. The aqueous dispersion of claim 15 wherein said wherein said first kosmotropic salt and said second kosmotropic salt are each individually present in an amount of about 1% or greater, by weight based on total weight.
 17. The aqueous dispersion of claim 11 wherein said aqueous dispersion has a bulk viscosity of about 2,500 cps or less.
 18. The aqueous dispersion of claim 11 wherein said viscosity-reducing additive is selected from the group consisting of glycerin, glycerol, alcohol, and glycol. 